I am quite sure that there are companies based in Malaysia somewhere and offering their wares on alibaba. These companies claim to have thousands of 5970 cards in stock and ready to sell them for as little as 100$ a pop. Though, it's wire transfer or western union only.
I am sure that if you negotiate hard enough they can get more cards and they will sell it to you even at lower price. Surely at those kind of prices prices 1Thps rig may sound plausible. I hope you hear from them after money are sent.
If you deal on Alibaba, there are two things to look out for:
1.) Gold Seller
2.) Escrow
If you have either of those, then you can certainly guarantee getting the goods. I've asked for some quotes from China, let's see how cheap they go for either the Black Edition or the Sapphire Toxic (Both 4GB DDR5) cards. Although I don't think the memory is that important, it's the number of cores (which is 3200) in those cards. I would NOT use western union or wire transfer as you will be had.