Checkout this site:
http://www.gpsmagazine.com/reviews.php
I'll warn you that it's possibly quite garmin biassed, but if you want to know what the GPS can do and how you'd go about using it, it's definitely a good place to start. Checkout some amazon reviews too for some real world perspectives.
On the site above, I'd probably look at the Garmin nuvi 265WT as it's inside your price range and identical to the 225WT just with the added bluetooth.
It seems to be a little confusing how Garmin have named their models - it's not chronologically-numeric. From what I understand, the models ending in 5 are the latest. So the 765 is an updated version of the 760. Took me a while to realise that the 255 is actually a pretty new model (or at least an updated version of an older model).