About the only example, that I can remember, of where an actual model increased in real value over the years was the Lionel, "Girls Train", from the 1950's. This story was told to me by a Hobby shop owner, and model RR manufacturer back in the 1970's. He and the "biggest" lionel collector in Mobile at the time, told me this story. How true it is, I'll never know, but it does sound plausible. The engines and caboose were pink, and the other two cars were definitely pastel in nature. Lionel manufactured a bunch of these trains, approximately 80% of which, never sold.
It seems that the girls that wanted to play with trains, wanted ones that looked like their brothers, or Dad's. Many trains that weren't sold were taken back by Lionel, and repainted and re-boxed, and then sold as regular Lionel sets. Some people had bought extra sets, or the dealer didn't send them back in. For collectors, who found that these sets were disappearing fast, they starting offering large amounts of money for a NIB "girls set".
At supposedly, one time in the recent past, a 1950's mint condition "Girl's Set" normally sold around $25,000.00, at a TCA meet. Not bad for an old set. IIRC mth, Williams, and supposedly Lionel as well, stared selling reproduction sets of this train. They don't cost anywhere near as much. But I understand that the price for the original set may still be at that price or even higher today.
