Well, since you don't tell us the size of your room, I'll say that if you have a huge listening space there is a pair of Dunlavy SC-Vs for sale on this site in your price range that are among the world's finest, though their cosmetic condition is poor, as well as a nice pair of Dunlavy SC-IVs for below your budget. Replacement drivers might be hard to get down the road, though, as Dunlavy is out of business due to the founder's death. As good as the other speakers mentioned in this thread are, I would take these speakers, had I enough room, they are classics.
If your room is 10 feet by 10 feet, though, I'd suggest ditching the idea of towers and looking into a pair of stand-mounted monitors. The room limitations would be too difficult to overcome with a full range tower speaker. Hence my question about your room size (as well as your musical tastes). While all of the speakers mentioned in this thread might be terrific in a system, they might not be a good match for a small room or the type of music you listen to.