I still remember my dad telling us in the late 50's you could get a retired steam engine from the railroad (In this case Norfolk and Western), for scrap price of around $5,000.00.
If only we had an extra $50K laying around and a place to store 10 of them, right!!! That price was for at least a 4-8-2, or 4-8-4, not sure about an articulated class A, or Y.
Recently there was the Bessemer and Lake Erie 2-10-4 sold to the Age of Steam museum. It was in Pittsburgh, PA, and the owners had been asking 1,000,000.00 for it for several years. It was landlocked, and had to be trucked out of there in pieces to Ohio. Not sure of the actual final price but I think it was less than 200,000. Age of Steam Roundhouse has purchased several engines in the last 10 years, including the McCloud 25 I believe, Hocking Valley 33, and others. But mostly that information is not made public.
Greg