I myself have had done pretty good as I buyer in the used train market. I bought on the Bay a used MTH Railking Y6B with PS 2 for $371 in 2008 and it still runs fabulously! I've also bought an MTH docksider on the Bay - no problem and it still runs great! I think when buying on the Bay its wise to always check out the seller's ratings. I will not buy from anyone with less than a 99.8% rating. Its important to ask the seller questions as well.
I know there are those of us who have had terrible experiences with purchasing off the Bay, however, that has never been my experience. I've been buying on the bay for almost 10 years now too. AND there are times when I have had to send items back .... a particular passenger coach was listed as o scale ... I asked the seller if this car was definitely scale ... she replied with "definitely yes" ... I received the car and it was not scale .... I contacted the seller and she paid for this shipping back and refunded my money in full. Hopefully she learned a lesson.
At shows I purchase used rolling stock and never have had a problem. Most of my rolling stock is used ... I could not afford all of what I have at brand new prices even discounted brand new prices. Often at shows I've picked up brand new cars from vendors offering estate sales. I've bought boxcars, passenger cars, new and never been out of the box, for great prices.
I just purchased at the Timonium show in Maryland, a Lionel ballast tamper and a K line Plymouth industrial switcher .... both run great! Of course I put them on the test track at the show before handing over the cash to the seller. That same seller had an MTH AS 16 switcher with proto 2 and low run time and for a great price. I was set to buy it and low and behold when put on the test track the switcher fired up but would not move in either direction. Of course the seller was embarrassed and blamed it on the Lionel 90 watt transformer and of course I did not purchase the engine. AND in all due fairness perhaps the guy had a point about the transformer for I had a strong sense that he was an honest guy.
Bottom line when at shows - ALWAYS test anything you purchase used such as locomotives, motorized units, operating cars, and accessories ... BEFORE you buy.
You can get some great deals on used ( preowned ) trains. You just need to be careful.
I do not purchase postwar trains any longer. Got enough of those still in my collection from childhood.... and they all run great too!
