I also have a non-avaition Garmin GPSIII, which was £200 from eBay about 8 months ago but you can now get them from one of the aviation suppliers for £149 (can't remember which one, but it's on a full page ad on the back of one of the recent flying mags).
Although it doesn't have the aviation database, it's easy to use by entering your own waypoints. I use streetmap.co.uk or Navbox to find the co-ordinates of my waypoints and check them against the latest charts to make sure they are right. Entering these into the GPS can give you airfields, landmarks, turning points or whatever you want them to be.
The screens on the GPSIII are configurable, so I have mine set to show altitude, speed, track, bearing, time to waypoint and ETA at waypoint. Marvellous gadget, but I also insist upon not using it some of the time to ensure I don't become too reliant.