High? Yeah... ok. Tell me where you can find a brand-new 5970 for less than $650-$700. They are better miners, and they are becoming very scarce now. There are many sites, such as Amazon, that are actually charging $800+ due to their limited availability. But sure, let me go ahead and spend like $175 more to buy a 6990 from Newegg (the total price will be around $800 after taxes!).
Or maybe you didn't notice that this card is brand-new? Maybe a used card could be had for less or something, but I'm not gonna mess around with crap like that.
I agree with eck, that is a high price. You can find 6990s for $710 if you buy out-of-state to avoid the sales tax. That's only 16% higher than what you paid for the 5970, except the 6990 is approximately 20-25% faster. So a 6990 would have offered you more bang for the buck...