Apparently, several owners of Bones (and Dwarven Forge) share their Bones and DF with their kids! Mr. Justin himself has a five-year old kid, who, I think, is the owner of the train in that picture (?).
eBay has various cheap junk O-scale trains, which would be perfect for weathering into abandoned trains. Or see if a FLTS has any for sale?
I figure I could use an abandoned train in the mine when I use it for a western setup!