I haven't tried any of the Chinese-made Quest motors yet (nor the Q2G2 igniter, either), but I can tell you that I was really impressed with the quality of the German-made versions. As for the price differential, it all depends on where you buy them, what sales you can take advantage of, etc. The prices that I have seen between the two brands are nearly identical, so everything depends on what discounts you can get. In my very limited experience with brick-and-mortar hobby shops (I have only ever been to three of them), I have never seen any that stocked Quest motors, but they are readily available from the mothership in Pagosa Springs and from various other online vendors.
MarkII