If you want a folder that folds as compactly as the Brompton, then your only option is either a genuine Brompton or one of its clones (Merc).

Bromptons sometimes show up on Craigslist for a good price but you'd have to act quick as they usually don't last long.

It seems that you CAN get a brand new Brompton for close to the $500 USD mark if you order the C-type. I contacted the gentleman behind Foldabikes.com and he replied stating that he could order it from England for you. It's just not listed by most dealers in the US.

Your best pricing may be to order a C-type from one of the dealers in England therefore taking advantage of the favorable British pounds/American dollar exchange rate.

At http://www.normanfaycycles.co.uk/ the C-type is being sold for 395 British pounds.

It would be great if Brompton allows the customer to subtract standard parts from the Brompton as they please.

For instance, I would like to buy just the standard frame and build up my own wheels with a Sturmey Archer 8 speed hub, add my own crankset/chainwheel, my own seat, my own pedals, etc. In fact, these are the items I'm adding to my current Brompton, but when all's done, I'll end up with a heap of Brompton parts that I have no use for.