If you don't want built kits I would try Etsy if you want to make a couple bucks.  There are less fees on Etsy than there are on Ebay.

Like someone else suggested, a VFW might be interested in military models.

If you live in a large enough city with a science museum, maybe they would be interested in some of them.

And car models could possibly be displayed at local dealerships or racetracks?

I would also ask a local hobby shop. My model car club has a display in our local hobby shop. We change out the cars every other month or so.