My coach uses an old Bfly Power 7 and it has amazing stability and control. Feeling is great and crispy thanks to Koto. I wanted something like that from a trusted reseller. I used spinfactory.de in the past and I had positive feedback for them. If they have a Sanwei solution for Koto blade, I would go for that 100%
Alright I understand loyalty to certain brands and retailers. And I'm hoping there's a Sanwei version of the Yinhe U2 as well.
If you want a recommendation for a trusted seller on Aliexpress I'd go with BEO Store. I've ordered from them before with no issues. They are higher rated than other sellers and probably sell more volume than any western TT reseller, so they have no incentive to carry fake goods.
If you don't want to buy Chinese, however, then that's a separate issue.