I check woot every day, and looky what they have today...
WOOT
If you look today (4/19/2006), they have a Magellan eXplorist 300 for only $105 shipped.

This unit has an 8MB mase map, but cannot take extra memory for detailed maps. But it will show you state boundaries, major roads (interstates and numbered state roads). It also has a compass and barometer.

This might not be ideal for your only GPS, but it might be perfect for a BOB or a backup, and the price is comparable to a non-mapping unit.