He is selling their parts.. how is he getting their parts information and reselling it? Does he send them a spreadsheet with parts to ship?

I would think having those records would be proof enough that the company knew about it because they were working with him. If anything the company might say you are not allowed to be a reseller of our products..

but the domain is his. If I was him, I would say, you can have the domain for $x0,000