Here is a good link for comparing unit features/specs. at Offroute.com, they also sell GPS. After much research and debate I bought mine (Garmin Map76s) from another Groundspeak club member right here,,see the Garage Sale posts here at Groundspeak. Local sporting goods stores/department stores sell gps, and garmin is giving a $30 rebate on some models. It seem that more geocachers like Garmin and have raved about the Garmin support, they seem to fix or replace units to keep the customer happy, at least that is what I have read.
http://www.offroute.com/gps-compare.html
It's such a brain traumatizing experience trying to decide