We had no LBR or LCS in our country when we started, and we got one just this year (LBR), and although we have great relationship when cooperation is in question, they don't provide us with bricks, and no one goes there to buy, because prices are really height, and we have built our own brick routes in last decade.
If I understand your question, you are asking how a young club and club members can get bricks in enough amount so you can make good, large events, and for them (bricks) to be as cheap as humanly possible? If yes, here is how we did it:
1. PaB network
we have befriended our international friends (usually friends from large forums, like Eurobricks or Classic-castle) to inform us when there is something interesting in PaB near their houses, and we would ask them to buy us cups. Then we had established routes through direct bus-lines, where we would give some money to driver to bring us packages (sometimes dozens of large cups). Drivers would be responsible for customs (i.e. they would never pay it, so we would not either)
In special cases, like USA PaB (we live in Europe), if there is something really good on the wall, we would buy less, and it would be sent by plane. I still have a box from Steph Mayo, where he wrote "wedding gifts" on large box, so customs wouldn't bother us :D I keep it, as memento :)
When cups come, we would meet up at pub, and then sort and share. This was a foundation of our friendship. We have been doing this even before we knew there is global network of (recognized) clubs, we thought we were alone in the world :) Silly, I know :) This was also start of great friendships with international AFOLs, and some of those connections keep our club filled with love even today.
We never figured out where a reseller can get 10.000 of sealed Rancorns, but ok. I guess when they are selling publicly, they are legally acquired. Re-sellers were our to-go source of bricks before we learned about TLG support. We found them usually trough other AFOLs, and on internet. Some crazy deals could be hammered trough tem, like 1x2 new bricks for 0.007 eur per piece.
Dark-sellers are, in our definition, sellers that keep tons of LEGO bricks in their cellars, and sell them in 50 kg bags. They also tend to sell them on markets near people who sell fruit, on weight, with same equipment you use for fruit (there was a place on market in Budapest that had few of them, and there was a dark-seller from same city that I went into his house, it was filled from roof to top with bags with unsorted LEGO bricks :)
Please note this was before the crazy explosion of desire for bricks in 2010-2018 :)
We utilize bricklink to its fullest potential - we are always on search for those crazy good deals where one can buy a large amount of bricks for extremely small prices - it doesn't mater if we need it now or not, every ELGO brick is usable, especially loose basic bricks. We learned to utilize notification and wanted lists, cross-searched with countries to the fullest. We also buy A LOT from sellers that have flat shipping - 10 eur for few hundred of KG of LEGO, it happened :)
5. Fleamarket and yardsales
once a member comes upon something like this, msg is sent immediately, and within 15 minutes we have 10 members browsing through bricks. We were like ants who found drop of honey :) in 10 minutes we are army of workers swarming the place :)
Good connectivity among members is a key (not just for this, for most things)
6. Other communities
We had luck to meet Romanian club(we are from Serbia) when we started - our relationship has since become less warm, but in those few starting years, I like to think we were unbelievable support one to other, source of a lot of joy and friendship, members connected internationally, and we traveled several times per year visiting eachother. Those connections helped us to have more reach for bricks than we would usually have, and also to establish connections with distributors that gave us unbelievable discounts.
7. Direct TLG support
Lugbulk, Project support - utilize this to the fullest. Influence your members not to pass out on lugbulk, and creatively brainstorm about projects - those bricks stay in the possession of club, and you can use them for something else after project is concluded.
8. Local Office
Local Office (LO), although for us was never source of bricks, was a great source of other assets - firstly contacts (we have upgraded 50% just from learning from contacts they connected us with), and POS materials (Point of Sale materials, like banners etc.). With good relationship, there is no end of what they can provide - but it also depends on if you have contact with same-minded person there. I was lucky that I made contact with Marketing Director who loved our "out of the box thinking" and our assets orientation, as well as our focus on making structure and logistics as profession as humanly possible for hobby club, to the point where we could stand toe to toe with professional event organizing firms - and we were utterly brand loyal, with "feel" for brick those professional firms didn't have.
I remember anecdote where I was at a face-to-face meeting with her, and after I said that we need any POS you have at hand, she took me to the storage area and said "ok, take what you need, as much as you can carry" - I am a very strong guy who had three more strong guys and girls hidden around the corner - we filled our van to the brim :) She laughed and just noted what we can't take, because of internal rules, and how crazy we were - and how nice it was we showed so much love for the brand :)
Please note that my approach to our LO was always like this: if you need us, we will be there, for free. You just need to cover basic costs (transport, hotel, food), for us to exhibit all around region - and we did.
Community team from Billund gave us wind in back and supported us with bricks, and LO supported us with assets Community team does not have access to.
Alas, with all the changes last year in Q4, we have lost contact with them too, especially with Marketing Director moving from that position.
Please note that we also had communication with other country LO, and they approached us from the side of force - we showed our teeth then and approached with a lawyer, and then they backed down.
Our regional LO approached us with open hands and with so much good will, and we responded in kind.
What I am saying, don't keep your head down - don't allow nobody to bully you, as I hear it happens, as every LO has different people working in them, with different philosophies and level of experience. Assert yourself (club) as a positive, professional force - nobody know more about the brand as you do :) nobody can create masterpieces like AFOLs can, no program can do it :)
So, stand your ground, be kind, if approached with force, respond in kind, if approached with love, responded ten times in kind :)
9. Members social connections
One thing that is prerequisite is a pack mentality of a club, members that love eachother and keep together no matter what is the obstacle.
Nothing can help you if you don't have supporting and caring mentality in the club, as offers do not get passed by, and there is not much will for making opportunities. Making a strong social connections is a prerequisite for anything club related. Also, having strong structure and logistics helps A LOT - we were teached this by a Community Manager in 2014.-15-16. Also, you need to have a strong and smart leader, or leading core group. If it is just a leader, he/she still needs to have support, as he/she will need advice and assistance from members who are proficient in some fields, advice, and moral support. Good leader draws strength from his/hers members.
For instance, I am not best in anything regarding LEGO in my country - I don't think I am in 10 best when building is in question, I am not the one who has most bricks, or biggest online reach, or most minifigs or most international or national friends. I am not the most educated one, or most intelligent one. I am not the oldest (heheh and not the youngest :D ). What I am good at is mix of inspiration, quick logical decision making, including integrity and I insist on logic, joy and inclusivity. I also inspire with commitment, passion and I believe I am great at empowerment :D I also push people into creativity and love to innovate - same thread can be found in many of other members from community. I love to think I am very kind when disputes are in question, and my background allows me to settle everything with few words. Why I mention this - I believe that MUCH of initial club development is on leader or leader core group influence and inspiration. After the club gets rolling in the constant evolution direction, then it can continue to evolve without constant inspiration from a leader - exactly what is happening right now in our club - almost every Team Leader has suppressed me in inspiration and innovation, and projects are happening left and right - and bricks just keep on pouring - and it is not enough - it is never enough :D
Few more years and our younglings are going to take over, hopefully we will leave for them good foundations for even more evolving. I am sure they will find ways of becoming better that we didn't envision :)
And also routes of bricks that we haven't thought of :)
Hope this text helped, I wrote it with a lot of love :) and with good music in background, while singing :)