They are targeting new or uneducated, in terms of pinball, individuals. I have purchased several machines from people with only one machine and they alway give EBay as their source for replacement parts.
Example, I bought a Corvette from a car collector that had the machine simply because it was a Corvette theme. He hardly played it and it had a couple broken plastics and a couple burnt out lights. Don't worry he said, you can get everything you need off EBay.
I informed him there are far less expensive places to buy parts which surprised him.
EBay is the perfect place to ripoff others.