I've had the similar problem myself. I was debating whether to upgrade to Radeon 9700 NP for $200 or pick up cheap Geforce Ti4200 to hold me over until more demanding games came out. I am currently using old Hercules Geforce2MX. Old card I know but it runs the games I play just fine. Games like Diablo2, Unreal Tournament, RTCW, Starcraft, WCIII, and TigerWoods Golf, and ProPinball games.
However, I've been wanting to play newer games like BF1942 and Medal of Honor and such, and I know my Geforce2MX isn't going to cut it. I tried to get Radeon 9500 Pro from Bestbuy for $150 but none of the ones around me had any in stock. I looked at Abit Ti4200 64meg at Newegg for $89 shipped but scary hardware reviews of the card turned me away. All other Ti4200 seemed to be in the neighborhood of around $120. I didn't want to pay that much for ti4200 so I was set to order Powercooler Radeon 9700 NP for $199 at GameVe.com when I saw Asus Ti4200 128meg for $99 minus $10 off coupon at CompGeeks.com. $89 for new Ti4200 128meg vs $199 Radeon 9700 NP.
I went with Ti4200 for $89. Radeon 9700 might be great but I don't think it's more than double great. Ti4200 is still great card and I should be able to play all the current games and near future games without too much trouble at 1028x768. Once Doom3 and HL2 and others come out I'll again reevaluate and see if these games are worth it and worth upgrading for. Prices should have dropped by then and lot better hardware should be out.