I live in Canada so it's harder to find great deals. The 6800 GS is around $270 + shipping but I can get the 850 Pro for $300 flat and not have to pay shipping. So they would come out to about the same price. Looking for an AGP card to last a couple of years then get a system upgrade.
Depends on if you need pixel shader 3.0 in the games you play. If it doesn't matter then the ATI AGP solutions are fast. That being said, the new 7800GS overclock edition cards from BFG, EVGA, and XFX look promising and since the launch they are around $300USD.