Dave-- can't tell about the TR500, don't have one, but I've gotten my parts from Helidirect, Heliproz, and GrandRC- it's hard to pick the best of those three, since they're all good. Helidirect probably has the best Web site, but Heliproz and GrandRC are good just the same, and HP has a better TT section than HD. Ace Hobby is always an option, but their prices are high.