Considering TZD's prices (ie: not low by any means) and notoriety, I really don't think its possible to buy out thier inventory and sell it on eBay for a profit. If this is what this guy is trying to do, he's sure to lose money.
Also, TZD has had the same dwindling selection for like...twelve years or something, so if you missed something you sure had your chance. I don't know of any store anywhere that has had the same game on the same shelf for that long.
...OK, maybe NCS's stock of Slime World for MD, but that's it.