I bought a GMC Thomas gasser for 2000 put about 700 into it.
Pulled seats, painted it green (tractor implement paint), 1” XPS insulation in the floor, bamboo flooring, installed an Orley wood stove, tiled the floor around the wood stove, installed a sink (RV bathtub) and a counter. We lived in it for 3 years, my daughter was born in it. Then we decided to sell it to buy a diesel International DT360a.
We sold the gasser for 5000.
I think it depends on your area. Here in southern Oregon there are lots of off grid type folks who are not willing to drive several hours to purchase a bus.