welcome to the forum =)
before everyone bitches you out, here's some nice cards in that range
you can get a GeForce2 GTS 32mb card for about $200 flat from onvia.com, link
here.
i'd stick with nvidia if i were you, and don't get anything less then a 32mb GTS card if you can afford it. you can rack up some deals by keeping your eyes peeled on this forum, and combining PriceMatching and coupons. buy.com has a 32mb card
here that you can use a $30 off $150 coupon for, assuming you are a new buy.com customer.
also check the For Sale forums here, there's plenty of people that'll help you, and you can find some awesome bargains there. just watch out- there's also plenty that'll try and scam you as well.
good luck =)