This shop deals with Brompton and is based in NYC:
http://store.nycewheels.com/folding-bike.html

My 2 cents:

Wouldn't it behove your LBS to "find the distributor" themselves, if they want your business?
Seems kind of backward to me. I mean, the reason they want to deal with the distributor is better margins for them. If they want their share of the sale, they gotta do the leg work! I ran a business for years and this makes sense to me.

Respectfully, deal with whoever has it in stock. They earn your business by taking the risk of having what you want on their showroom floor - local or not.

BTW: both the Brompton and the Dahon are fine bikes. You're going to pay a premium for the Brommy on account of being make in the UK. It's worth it if folded size is of utmost importance. If you can live with a slightly bigger folded package, the Dahon would save you some $.