Just to give some experience I had.

The site TTI-US listed above, I bought my JR radio interface to use with the FMS sim and works pretty good. Transaction and delivery was also fine.

http://www.airborne-models.com/index-2.html => I bought my last plane from there, a piper J3 cub wipped wing and the deal was great. The delivery was amazingly fast.

Other than these, the list already given is the one I have.

nilo