I'm in the market for a dedicated GPS as well. Right now I'm using my Android with the "Cue Sheet" app coupled with "Ride with GPS" for mapping rides. It works but it's clunky. No voice prompts and the tracking is really slow. If they could make this work with Google Navigator Garmin would go out of business. ( I own a Garmin car GPS and Google Navagator beats it hands down )

As it stands Garmin looks like it is the only one offering voice turn by turn. I could get by without voice prompt as long as there is a tone warning before the turn and the tracking is fast. That I could deal with. If the Garmin 500 offered that I'd be on in real quick. I'd like to keep the purchase under $200 though. Ebay might be my best bet.