I like my Great Planes Master Caddy, but considering how much time I put into I suggest the prebuilt one for the extra 10 bucks. http://www2.towerhobbies.com/cgi-bin...?&I=LXPS86&P=7
One thing I did build was a collapsible wheel dollie that I can put my flight box on and pull it with rope, like a wagon. Makes for the long walk from the parking lot to the flying field that much easier.