There is a gas engine show with a huge flea market (sell and swap) in Portland, Indiana late August. One of the largest steam shows is mid August at Rough and Tumble in Kinzers, PA.
Back to Indiana.... there are often steam items for sale at Portland.
Have a great trip!
Gil
The Portland In. show is very large (recommend renting a golf cart ahead of time) I have been to it a few time & during the show days golf carts are allowed to run all over town.