$80 and under? Your current graphics card is probably better than an $80 card, figuring probably the closest nVidia card is a 9800 or an 8800, from about 3 years ago, and I don't track ATi cards, because they don't come with basic fundamental features that nVidia has.
EDIT: my old 8800 could run Crysis on mostly medium some low, but if you want to run Crysis on all high or all very high, you're going to have to invest a good $300.