John
I agree the Play Value and enjoyment is the most important factor in the worth of our trains. 99% of my postwar trains were purchased, well used, and would be about as valuable as the price I paid and some less. My other items like some of my antique furniture and used tools also would be worth less than what I paid.
But I have a several items that are worth dozens of times (based on recent completed eBay auctions) what I paid for them and they also have a great amount of literal Play Value. These are vintage 1970s, good quality stereo receivers. They also have great true Play Value by playing enjoyable music on LPs, Cassette and reel to reel tapes, CDs, AM and FM radio and streaming. Some turntables have all done well on real value and Play Value too, Real Win Wins.
Charlie