I cannot speak for other photo equipment retailers, but for my store I do my best to be consistent by paying 50% of what I think I can sell it for. I came up with that "crazy" formula from all the record stores I've worked for. Obviously a seller can get MUCH more by selling on ebay, craigslist, apug, etc. or KEH which does about 40% of retail if I recall. The big guys should pay MORE in my opinion, but they don't have to, so why would they? I would pay more if I could afford to but I am one of those small businesses that is in it for the silly reason of liking analog photography! I don't know if this info is useful to you or not, but I suppose you could check the prices B&H has on items like the ones that you sold to them to see what % they gave you.

Matt