Ive probably bought and sold 50 cars or so over the last few years, as a buyer i research what things are selling for first, what issues they have and what to look for and any offer i make would be based on that, only a tosser or a gypsy would ask for half off in CASH and as a seller especially with vans you'll be deleting many of these but a genuine buyer will turn up.
dont do it so much now just every now and again as bargains nowadays seem to be bargains for a reason, i.e., they are fooked