Have no folding bike myself, and not much experience apart from the awkward 1970ies folding bikes, but this is a very good forum, Brompton should be in the classic/vintage subforum:
http://www.bikeforums.net/bike-forums/
http://www.bikeforums.net/folding-bi...ahon-tern.html
(but you can ask for it anywhere, everyone knows them there)
We used Bromptons in the swedish marinas from time to time, since they stow away easily in the yachts, and they are great for short rides. I still think they are too expensive for what they deliver, but they are 'hip' and you pay the brand. You can of course sell them again, at appropriate (high) resale prices.
There are special editions of the 'Brompton' from time to time, with a different colour or outfit, often less expensive.
Also this: Which is the best folding bike?
https://www.theguardian.com/technolo...da-dahon-birdy
If you know a bit about repairing bicycles you can buy it via the internet (probably using the Amazon link at Subsim
)