if a person likes to restore cars, and then has to sell that car to fund another. perhaps he needs to either : be wealthy,... do ALL his own work, .... not restore a car to the extent there are NO buyers for what he has in it??
as cosig said, what you sell anything for depends on the market, has nothing to do with what it costs to get that project from " out of the weeds" to "restored"! sad fact of life.
