Who knows where the deals...

...for automotive GPSes can be found? I have a venerable iQue 3600 that's having hardware issues here and there, and also needs a map upgrade badly (which Garmin doesn't make easy). I need to drive through Boston next Friday, and being a wuss I'd rather A) have a machine that tells me where I am and B) have it both Big Dig aware and knowledgeable on how to bypass around the bits that are collapsing.

As I'm not nearly as wealthy as I am handsome, and not so handsome to begin with, if someone has a recommendation of where I can find a decent auto GPS on the cheap, this would be a lovely time to give it.