CM Wasson [foldabikes] sold one thru his site , but he is in California, and actually has retired and shut down his shop and website.
he was the 1st dealer in the US of Bromptons , now there are so many more.
I Bought my Schlumpf- Brompton Mountain drive crank and some Fizik Vitesse for Brompton saddles from Him .
And several replacement parts to improve My Mk 2 , which I have recently sold..