Initially I assumed these were review cards that have made there way to general sale. Looking at it further, it appears that particular listing would still not arrive for another couple of weeks (in line with general sale - so they're still preorder cards).
Ultimately, there's only one listing, so it's not a fair reflection of the pricing. It's someone listing it for a ridiculous price, hoping someone will bite.
There's always someone out there willing to pay over the odds to shop from somewhere they deem more reputable (like Amazon). The seller will also ship worldwide, so there's always that potential market too, where 1070 releases will be later.
As a side note, I just reinstalled my OS and decided to try out another antivirus, which included a Chrome extension, and I hit your link & it popped up suggesting the lower priced eBay listing for me (how nice, yet unexpected).
http://www.ebay.com/itm/like/112022980525?item=112022980525&lgeo=1&vectorid=229466&rmvSB=true $649