I don't have anything to do with Lionel trains, but I did note on their website that they have made or are making N scale die cast unpowered locomotives of various types, selling for about five bucks each. I noted an F3, GP9, N&W 4-8-4, NYC Hudson, GG1 and the General 4-4-0. If you go to this link and click on "product navigator", then "die cast", it should get you there. Might be a good inexpensive item for museum gift shops.

http://www.lionel.com/Products/Findex.cfm