well, agp 2.0 runs at 1.5V and 3.0 runs at .8 v, so the only real difference is the voltage, so a 4x card will run great, just lower voltage, and a 8X card will run ok, just higher voltage.
ATI x1300PRO 256MB 4X/8X - $93.99 Nvidia Geforce 6200 256MB 4X/8X - $69.99
seems all the tests that have compared the 2, the ati was a heartbeat faster than the 6200, but its almost $20 more, so i guess you can save 20 bux for almost the same performance
closest i can get without going over $100