I think that somebody is buying up all the inventory to try and drive up prices in the secondary market.
Lots of unopened 7970 and higher level AMD product available on eBay at high buy it now price, not terrible out of the ordinary, but not as much used AMD product at that level though, so I think some ass or group of asses is manipulating.
Maybe somebody is/was trying to get ahead of demand for these cards with all the press on virtual currencies, bitcoin and lite coin.
Recently I tried to make it sensible to buy a new 760 or 770 for a rig I'm building, but will hold out for a 280x at $300. NVidia pricing just isn't competitive.