I think if you want to do this, you should share with your friends (that you know them and know how to go to their houses) Because, the discount for decks even if you buy a lot is not too much. And it's not easy to get someone to responsible for all.
I think instead of buying from a group of people in a forum, people will choose to buy directly from the shop, because they can ensure their order. It's not really that needed to get a small discount and take a risk.
Just a thought from me.
No offense.