Ladies and gents, we have a new low! Buy.com has the Magellan RoadMate 2200T GPS for $59.99 shipped (after a $30 mail-in rebate). It's a refurbished unit, but it's also the least-expensive navigation system I've seen yet.
Needless to say, this model is a couple years old, so don't expect a lot of bells and whistles. It does offer text-to-speech, music and photo players, an optional traffic-monitoring kit, and a "smart detour" feature. Hmmm. Come to think of it, you get some bells and whistles, after all. It's even waterproof!