This is going to probably be offensive, but that site is absolutely everything I would figure a Chinese C2C or B2C website would be. Just an overwhelming of the senses.

I have no reason to assume the frame isnt quality and wouldnt be legit, its just shocking that a small builder would have access to that many models of tubing. I dont know which ones require specific training, but am positive some domestic builders dont use one brand and model or another due to not being certified. Surprising this seller has access to all of them.

If all that is legit, those are some really well finished frames.