I have been buying trains on eBay for over 16 years. Most are great, some have been bad.
I just bought a K-Line NYC Alco set for $35 shipped that was listed as not running. I figured it wouldn't be too difficult to get them running and if I couldn't get them fixed, then I would have some good parts. The only thing wrong with them was too much grease on the gears that caught a little piece of plastic. A little cleaning and they run and look like new.
I haven't had an issue on eBay that couldn't be resolved.
Marty, it's your prerogative how you conduct your business, but I really don't see the logic in refusing a repair job just because it was purchased on eBay. A broken train is a broken train regardless of where it was bought.