I spend a lot of time on ebay looking through various road names for items, probably a few times a week for the past 4 years. I see a lot of repeat items and what amazes me how you can have two identical items in the same condition and one may sell for double the other with same shipping cost.
For example, there was a bachmann spectrum C&O George washington set that sold 2 weeks ago for around $600 with 20-30 bids to get to that price. That set has recently sold for $150-250 from other sellers recently. When you get down to it you are getting a non-sound loco (heavy 4-8-2 spectrum model that pops up frequently on its own for $75-100) and 7-8 spectrum heavyweight cars.
There must be people out there that really get caught up on trying to win a model. I know I listed a bunch of normal 54' Atheran blue box covered hoppers kits one year, most sold for $7-8, but the MKT one (nothing special, not even a special run or rare) went for $25. I was happy, but I searched and found 3 more just like it that had sold with no bids and low price within days.