If that's your budget and the price difference is what you say then you should be looking for an HD4670 or 9600 GSO. They are pretty good gaming cards for low resolutions(1280x1024 and below.)
Look for a DDR3 HD4670 rather than DDR2 but ignore differences in memory size(512mb vs 1gb) because the card can't effectively use more than 512mb.
For the 9600 GSO there are a lot of different varieties. Some are good and others are pretty bad so ask here before buying one.