There is the 8800GTX 768 at $500-600, the 8800GTS 640 at $379, 8800GTS 320 at $295, and then the 8600GTS at $220. Below that come the 8600GT and the 8500.
To answer your question the cards between the 8800GTX and the 8600GTS are the two 8800GTS cards.
Looking to build a new system D? Processors are particularly cheap these days heh.