I recently bought a Garmin Edge 705 bike computer to help with my training for next years Vätternrundan (a Swedish 300K bike race around the second largest lake). It was quite expensive in itself which led to a small chock when I saw the price of the maps – almost 50% of the price of the GPS unit.
I googled for free maps and after a while I stumbled upon openmtbmap.org. They package Open Street Maps for mountain biking, hiking or bicycling. So far I have only used the maps a couple of times and they have worked just fine. In the end it all comes down to how detailed the Open Street Map is for the required area.