Wholesale Slabbed Coins

I sometimes one or 2 sellers on ebay selling a hundred or more slabbed coins a week, not excessively expensive, but decent coins, like ms65 morgans, ms64 british half crowns and shillings, Indian victorian rupees, and a lot of slabbed medals (basically stuff that retails for a couple hundred or more but under 500$. The slabbed medals I thought was iteresting because few auction houses slab them. But the ones that do like Stacks don't sell too cheaply like this guy has. I was wondering where these guys get their products from. Do you think they just buy by auction and hope that their own auction will get a higher price? I don't think so. There must be some supplier selling to them directly. Any thoughts? Are there any suppliers of slabbed world coins in the 100-400 dollar range that sell direct rather than by auction? Or could they be going to coin shows regularly and just making deals? The thing is, I see many of the same coins week after week. So I'm assuming that regular collectors wouldnt buy many multiples of the same coin and at the same grade.