Selling OEM products on Amazon???

So the other day I needed a part for my washing machines. The repairman came over and was installing it and I asked if the part is original and he said it is not but it is OEM. I entered the OEM number and brand name of the washing machine on Amazon and the price is around $90 but he wanted to charge me $150. Then a discussion started so as to who can manufacture these. He said all these products are made in china and anybody can have it manufactured for them. I clicked on the seller company name and you can see the seller person name and address unless it is an LLC. When you enter that name on google, you can see the Bill of Lading and find out where they imported even the manufacturing company name and address phone number of the company in China or South Korea.

Nevertheless I paid the $150 and he probably bought it on ebay or some local place for much cheaper but what trigged my mind is, can anyone manufacture these?