But please keep in mind that the OSM data ist still not reliable for secure routing in Europe. When you want to spend some money, try to get a professional routing device like garmin, tomtom, navigon, medion etc.
With some of them you can log your trips in gpx or nmea format to contribute to OSM.
If you want to be able to choose between OpenStreetMap maps and commercial maps on the same device, then I know only of Garmin brand devices. But routable OSM maps on Garmin devices is in beta stage at best. Some get great results, some are dissapointed…