Just my humble opinion, but prices are through the roof on everything and going higher. Any collectible from classic cars to model trains is bringing record money.
Concerning brass models, as long as it has a decent paint job, the sky seems to be the limit with some buyers. The prices paid for these models in discussion is utterly ridiculous...........especially that tank drive model.
Yet, I see unpainted models not selling in many cases, so buyers are wanting RTR models, like they would get from Atlas or 3rd Rail or ???? There's a mint or new unpainted Westside Bigboy on EB right now for $1500 and no bids. That's a good price for that model, especially when compared to the well used, but painted, MG and USH models that are selling for $2000+.
Another interesting point is some of the current O scale listings on EB are being bought at auctions and then fliped on EB for big mark-ups. I followed one EB seller (Trainbud) and see where he bought all his recent EB listings from a January Stout action and then sold them on EB. KEY E9's he bought for $1000-1100 and then sold for $4K. PSC DD-40 and DD-35A & B purchased at the same Stout auction for around $1000 each (very nice models) and listed them on EB for $1999. I don't see them, so assume they sold. I guess I should consider him enterprising for making money, but most of his prices are gouging and that just doesn't sit well with me. If he were to take these models to a show, at these prices, he's get laughed out of the hall.
"The times they are a changing"
Just my $.02.