Spare parts means you haven't built enough planes yet! Get busy!
Brushless motors are essentially maintenance-free. No brushes to break in, and the only wear parts are the two bearings, which last practically forever under normal circumstances.
IF you're worried about the low-voltage cutoff and LiPolys, don't. You can land and test the voltage every few minutes for the first couple of flights, just to see exactly how long you can fly. Usually, you don't have enough power to fly the plane long before the batteries get into the danger zone.