jonjonbear,
Check here for the latest pricing.
http://www.pricewatch.com Look under Multimedia --> Video Cards. You can get a good GeForce card for around ~$30-$50 depending on what you would like to spend. Anything with 16 MB would work ok, 32MB or above would be fantastic.
At home I run a 64MB Elsa GF2 Ultra at 1600x1200, which is an expensinve card, and it looks awesome. At the office I run a 16MB TNT2 Ultra at 1280x1024 and get about ~60 fps or so.