Aircraft Engine-only Kits?

At Model Expo, we're always trying to figure out what our modelers really crave. We have been thinking about
offering up the engines of our Model Airways as "engine only" kits. Most likely, we would include a propeller - question is, does anyone care / want simply the engines?

Curtiss OX-5 in-line V8 water-cooled engine

180 HP six cylinder Mercedes-Benz motor

Clerget 9-B rotary engine