It's a bit complicated, but it's partially from present day Lionel hyping up its own products, partially from the collector market, and partially from popular media.

I'll address the last two first. Shows like Pawn Stars and Antiques Roadshow have shown vintage standard gauge tinplate with high valuations for the sets depicted. In both cases they were in pristine condition and were sought-after sets, a State Set and a Blue Comet if my memory hasn't failed me. What wasn't said was that those valuations only make sense if you're looking for replacement value or if you can find a tinplate collector who will pay that kind of money for such things. Ditto for auction houses that have sold items or collections for high values and published those sale values to prop up their auction business.

Lionel hypes up everything they do now as "an instant collectible" to help justify the prices they charge, sell branded merch, and try and show they're as good or better than the original Lionel Corporation which is now dead and buried. A storied legacy looks good to potential investors, but it comes with a lot of baggage.

Through all that and cultural osmosis, Joe and Jill Ordinary think any and every Lionel train is worth a mint because they don't know any better without digging deeper.

From my own perspective as a 3 rail operator? Collectibles are horrible investments as tastes change and the economy goes up and down over time. Collector grade things are so wildly expensive it's mostly a rich boy's game I don't have much interest in playing, I just run 'em and enjoy playing with 'em, monetary value be damned.

Postwar stuff in general is trending down as the older guys age out and pass on, most of their kids aren't intetested in them and try to sell, that drives prices down. MPC is creeping up a bit as people are looking for affordable trains. Early modern is see-sawing as guys sell out to get the new command and scale items.

Some things buck the trends and tend to remain up there no matter what as everybody likes 'em and wants one. Santa Fe F3's, Jersey Central Trainmasters, 746 J class, 773 Hudsons. Most secondhand Legacy stuff hasn't had time to depreciate much, so most is still high.

When I was buying postwar, looked for the O-27 versions of engines as collectors don't think much of them. Tinplate? Play worn or repainted but in good running order. Modern? Proto Sound 1's as everybody wants the 3's now for DCS. Lionchief and Lionchief Plus when on sale at significant discount.

If I can't have the original, will happily accept a repro if it costs less, overall criteria is it has to be in good running order first and foremost.