One of the little Garmin's (Street Pilot I series) would probably suffice for your needs. The Street Pilot I2 is black and white, the I3 is color, and the I5 is color and has a hard drive. You can pay anywhere from $250-$500 for this range of models.

But you'll have to do your due diligence if you're going to get your best deal.
CNET.Com has some good reviews, but the best site is run by a couple of ham operator guys who branched off into GPS. These guys have some really comprehensive write ups.

http://gpsinformation.net/

There's new models coming out - the Nuvi350 which was only a couple of months old is already being replaced. You could not find a Nuvi350 for less than $800 a month ago, now they've dropped down to $700. Maybe you can catch a higher end model on a price drop.

Good luck.