If you need a GPS, get a cheap TomTom or something for a hundred bucks or less.
I keep thinking of getting a GPS-based bike computer, but I just don't see the need. It has to be recharged more often than any regular bike computer in existence, and, IMO, it's doing too many things too much of the time.
What I mean about that second point is, if you know where you're going, you don't need GPS. If you're lost, you're not very far off track -- you're on a bike, not flying an airplane.
So, I'd say that you'd get a better bargain if you get a separate GPS unit and only turn it on when you need it.