[x2drich2000]

I know I've said this before, but being a card dealer is not like a typical business. Acquiring inventory takes a lot of effort and knowledge. You can't just go out and order more. Low margins may work for some, but it is a lot more hassel (cost, bidding, offers, tracking inventory, scanning, listing, accounting, etc) to replenish the inventory. If you have the resources to hold the inventory until you find a buyer, why sell low and go through that effort to constantly replenish stock? Set your price and wait for a buyer. If no one buys, eventually they would need to sell or go out of business, at which point they would be selling as well. Obviously Dean's, 707, etc must be doing something right that works for their business model or they wouldn't have been around for as long as they have.

As far as where and how much they pay for cards, my guess is in most instances there isn't a special resource no one knows about. As others have indicated here, they are competing with others for the cards they buy. They were just willing to pay more than someone else at that moment. If you're upset that they won the card and are now charging more for card you want, perhaps you should have put more effort into finding the card and bidding more to win it. If you're upset that they bought a card from you and are now selling for more, perhaps you should have set a higher price or not put it in an auction.