For that kind of money I would buy a used 6970/50. You can find them around 100 bucks and get 470khs out of them pretty easy.
If warranty is what you are worried about XFX is lifetime, but they are known for using cheaper components(not necessarily that they fail easily but they don't overclock as well)
Also, takes me back. Ever played duck tales? I remember our second computer was so fast (cyrix 100mhz cpu) that you couldn't see the hook spinning on the rope.
you must have some 6970's sent from heaven to do 470khs
I'm able to get 450khs on an ASUS 6950 unlocked and oc'ed but never hit 470
I use all different brands and achieve the same result.
6950 shader unlocked or 6970 =470khs
6950 standard 430khs
I even get these rates on the extra cheap visiontek 1gb $169 refurbs (they have been running solid for a year now and I got over half of them to unlock)
and yes they came from heaven(newegg)