Most of those Chinese frame websites are selling OEM quantities. I've never found one that ships just one. If you do find one that will sell you a single item, good luck with it arriving with no damage, and good luck getting any help if it *is* damaged. BTW, if you look closely, those are not even photos of frames, those are digitized CAD drawings. Those guys may not even have ever produced one of those frames. They probably know a guy who knows a guy who works for one of the handful of companies able to produce a frame like that, and they think they can just send them a CAD drawing and get a frame back that actually works.
There was a guy at Veloswap last year who had bought a bunch of Chinese 29'er frames and was trying to sell them. He said it was a terrible experience.
I don't know what Zinn would charge you to build a Titanium frame, but at least you would know what you were getting, and I'm sure he would be willing to give you advice on the electronics. Since the motor/battery/electronics run around $2K, just add $2K to whatever build you would want.