I upgraded my card last week.
Did a lot of reviews, a lot of research. You can look around yourself and you should find jafergon's ATI X1950 Pro 512 card is pretty much the last great and fastest card you can buy for AGP.
Newegg has it for $224.
http://www.newegg.com/Product/Produc...82E16814102071
Check out
www.Tomshardware.com for reviews, tests, comparisons.