Distributing Computing Korea is looking for purchase agents internationally who are willing facilitate the purchase and shipment of graphics cards (namely the ATI Radeon HD 5850 1GB) to South Korea for use in large scale mining farm installations. An estimated 20,000 cards will be purchased before the end of 2013.
Unconfirmed sources indicates that the 5850 is EOL, so once the current supply dry up, you won't be able to get any more unless specially contracted I suppose. Even then, AMD would probably push you to make them from existing 6950 chips or something. But since you can't commit to a single large order, you're not likely to get any new 5850 even by this year end.
Especially since the 7000 series is almost ready, I don't see AMD producing more than 2 generations of GPU at any one time.