Bearings are surprisingly generic by size. Google wheel bearings and try to find a local bearing store that deals with only bearings and the like. Don't use an auto parts store. The guys behind the counter at a good bearing store usually know their stuff. Tell them what your application is and show them your old bearing(s) for sizing purposes. Then buy the best ABEC grade you can afford and tell them you DON'T want Asian made products. There are usually at least 4 different grades of most bearings in popular sizes. The higher the grade the tighter the tolerances and the better the quality. I've had good luck with European manufacturers like F A G and SKF. McMaster-Carr might be a good mail order place to start if there isn't anything close to you locally.
tohttp://www.mcmaster.com/#standard-ball-and-roller-bearings/=10gx5sh
Chum lee