Is it the quantity that you can't get, or are you after discounts?
I've found that the case price at Sam's is usually very good, and if the item you want also happens to be on sale, their price is usually unbeatable. I've bought as much as 1000# of butts and 400# of brisket from Sam's before and they didn't even blink an eye with 24 hours notice.
There usually isn't much (if any) discount on meat items from a food service supplier. My Sam's club price on pork butts, brisket, ribeyes, and chuck roll is within just a few cents a pound of the price from my food service supplier, and usually a few cents lower.