we have a listing of moped army a-ok'ed parts shops listed at our site on resources - articles - recommended moped shops. (http://www.mopedarmy.com/resources/articles/mopedshops/)
try handy bikes first at (614) 299-0550 as you can speak with a knowledgable person right away on the phone and most importantly they have a lot of parts. also they're cheap and they ship fast. i can't recommend them enough.
after that i'd say www.themopedjunkyard.com. i've had more experience with them but that was only because i wasn't fully aware of handy bikes at the time. but they have a lot of parts and also ship fast it's just that you have to order online so you get no assistance and also they aren't exactly cheap. but i've seen much more expensive options.
hope that helps