I use a Garmin Nuvi 1490T that I got for $100.00, I put an anti-glare film on it and it works great with gloves, I just keep a sandwich bag handy if it rains. Somebody steals it, not as big a deal it's $100 dollars.
Yea that's what I do. For the motorcycle, I go cheap! If it gets lost, stolen, dropped, rained on, whatever.. it's not a big deal. (Mind you, it doesn't rain here like it does in BC) I have a Garmin and a Magellan. In my experience, the Garmin is far more reliable. Sounds like you have a pretty good idea of the features you're looking for.