The GTX is my current favorite card, and apparantly others as well, hence the prices.
Its VERY quiet (silent?), and its very fast.
The GX2, while the fastest card on the market today requires additional thought as to what motherboard you put it in, to some degree.
But they are great cards, exceptional engineering to have that sort of power in that thermal envelope.
The X1900XT is the other card I like. Its price performance continues to skyrocket, and while Im not buying the idea of HDR+AA today for any sort of high res FPS-styled action.. I'm a big turnbased gamer, and someday who knows.. maybe the XT wont be too slow by the time a killer TBS game is released with HDR+AA?
I can say this much, if Heroes of Might and Magic 5 supported HDR+AA on ATI only, I'd be using ATI. Period. I'm a fanboy for the HOMM series, have been since HOMM1 when I needed to update my video card to a VESA compatible one to play it on my 486
Things I dont like about the XT is the cooler, its loud. I'm also not a fan of CCC or any of ATIs longterm driver support. I also dont like the brands that ATI cards are offered in.
I like Evga and BFG, and have had nothing but exceptional service using Evga's Stepup and BFGs RMA service.
Overall, I'd have to give the nod to BFG over Evga. Though thats not even really fair with how well I feel I've been treated by both.
For stock coolers, the GTX cooler is the best hands down. The card is fast, and does the job very well. Among the NV vendors I prefer, and the cooler, and the long term driver support, I also like 8xS AA.
Its simply an amazing AA mode in Heroes of Might and Magic 5. I dont think I could move to ATI because I am indeed so hooked on this.
Losing my 8xS + killer/quiet cooler thats on the GTX would be to much for me to lose.
Its my pick for "card to have". Which is why I use one

I bought mine for $400. Not bad for a BFG, would do it again in a second! I would have been willing to pay more, if I knew how much I'd fall in love with this card (moved from 6800GT SLI to 7800GT to 7900GT to 7900GTX).
I've owned dozens of video cards since my first PC (286), and this GTX has knocked out my precious GF2 GTS as my all time favorite video card. That GTS lasted me a very long time, but I enjoy and appreciate this GTX more so and I never thought I'd be able to top my GTS on my list of all time favorite video cards.
Maybe thats why prices are so high.
Also, cards like these, instead of selling for $20 new retail prices eventually... tend to just dry up/disappear from the market. People expect the high end cards to continue to drop in price forever, and that never happens (because that'd be impossible as they stop production).