You might be able to tap into a similar co-op already in existence. If you aren't already buying in bulk, wiht a family of7 it would probably be worthwhile to go for the big tubs of oil, 25# sacks of rice and so on. I just bought coconut oil from Bulk Apothecary in 1 gallon buckets, but they offer bigger buckets to apparently anyone. I'm sure there are suppliers for other stuff like that, maybe not all in 55 gallon sizes, but definitely bulk compared to grocery stores. Also, if you have a grocery store that sells in bulk, they'll often give you a discount if you buy stuff in whatever size they stock their bulk bins with. I've bought 25# bags of flax seed at WinCo that way when it was cheaper than the feed store for a while.