I would expect that customers who are willing to spend $20,000 and up would want to go to a gallery where they could see the art in person, and where they could

I would expect that customers who are willing to spend $20,000 and up would want to go to a gallery where they could see the art in person, and where they could get a certificate of authenticity from a reputable gallery. If I were buying expensive art I would be leery of buying on Ebay for fear of getting a fake.