In that case, first place I’d look is on EBay to find ‘Books being sold for parts. You’re not going to have a lot of luck getting an OEM keyboard.
As far as where we got most of our parts from, we usually went to MobileSentrix or MobileDefenders. They stock parts for a lot of phones, even replacement displays for iPhones, Surfaces, and Switch. However, I don’t recall if they require some sort of business account.