Wouldn't doubt at all that the chassis is sourced from China. I don't really see that as a problem. I would guess most amp makers are sourcing chassis and head-cabs from China. I would be more interested to see the quality of the components inside. Aren't they mercury magnetics at least in the transformers? I believe that is the case but don't quote me.
There are very few decent reviews of this amp or any other dumble style cause few youtubers have the ability to shoot a video with a cranked up 50 or 100 watt amp. Most of the demos sound like crap to me on account of that. If I review a Twin Reverb and can only get to 3 on the dial (which seems about on par with the Sweetwater and Ronquillo A.N vids) you aren't even getting the amp to a place where the true, best tone would be heard.
As for 4k, yeah that's steep. But Two Rock and some of the other makers are in that price range and 4k is basically the new 3,200 bucks, which isn't really that extreme for something boutique and handwired. Or are these just a PCB? That might be a deal breaker for me but short of selling my house and relocating I can't honestly even consider an amp at that price range anyways.
If I ever decide to go this route I'll probably be shopping Ceriatone cause there are more reviews of quality and the better reviews do sound good. They have a good rep, quality parts can be used, and the price is about half. Maybe a steel string singer but I would be looking at 1x12 combos for the portability.