Around here, you paid full market value (for one that needs clean up and servicing). Trikes are a very limited market, hard to find them, harder to find buyers for them. Nearly impossible to ship, and Walmart sells one at a relatively low price that is shiny and new which is what most buyers want.

Now if you are in an area with a concentration of retired people, demand would probably be better. Even then, I have been retired for many years and still ride a traditional road bike. So not all retirees want a trike either, but some do.