No photos from thrift shops like Nick does, but I did once score a nice boxed Wilesco D-5 from an antique store, once a year sale, for $15, but was told that the "big" steam engine had sold half an hour earlier. Of course they had no idea what the "big" steam engine might have been!?!?
Got a Mamod MM2 in nice complete condition at a yardsale once for $8.
Then there was the yardsale, just last year, where I picked up a good condition Jensen #100 workshop for $25, and was told they sold the steam engine that went with it for $40 just a little while before. Didn't really need the workshop, but it was too good a deal to pass up, so I took it. About a week later, I saw a want-ad in the local free advertiser asking for the workshop from that yardsale, by the person who bought that engine. Small town syndrome, it turned out that I knew the person, and made arrangements to meet up. Ended up instructing them, so they could teach their grandchild how to operate the steam engine (tin based Jensen #25), along with what else would be needed to run it, and where to get parts for it. Sold them the Jensen #100 workshop for just what I paid for it, and offered further help if they needed it!
Hope the kid really enjoyed it, as few kids get such gifts these days I'm afraid!!!