Very rough cost estimate I got was $885 (titanium). That's no where near where it'd have to be. It would need to really be no more than $400 to make it an attractive option. Otherwise, buy the cheap Brompton, gut it, and sell the parts. The problem with the outsourcing for something a bit more complicated is also that it's quite quite likely one of the moving parts is going to have an issue. Round trip shipping to the east is going to top $100, if they'd even warranty it.

This might be an a good "learning" project for someone to practice frame building, but it'd be nice to see a few reports of steel costs before calling this stuff off.

The other "problem" with most of these lower cost folding bikes is that they hold their values incredibly well, sometimes aquin to what normal product price increases date them back to.