There was a fellow in Hastings, MI who had several dozen Kaiser and Frazer cars that he had amassed over the years. His son realized that his elderly dad was never going to do anything with the cars, many of which were driven to where they were parked and decided that it was time to sell. I, along with several other club members, drove out for a look and while some were restorable, most were not. He had 6 or 7 HJs parked along a briar patch that were, aside from the rear bumpers poking out, completely obscured by the bushes.
The father looked at the cars and saw them as they looked the day he drove them home as well-used cars. His son was more realistic and saw that most were parts cars on a good day. Prices on the cars varied widely, depending upon who you spoke to. A decent 51K was $350 from the son, $1500 from dad.
I suppose what I'm trying to say is that sellers have an idea as to what their car is worth. I know that my $4500 Jeepster is worth that based on what's on ebay and other sites these days, but I'm equally as sure that someone's going to stop, have a look and declare it a good $2500 buy. If that happens, I'll politely beg off and keep the car. Ask what you want for a car, if it's a fair deal, it will sell. If not, then either the market is down (try to sell a nice Model A Tudor today for $15K and you'll still have it a year from now, when 5 years ago, they brought that or more) or there's just no interest in that make/model today (think late 70s full size Ford cars).
The HJ market is fickle. Those who want a body and frame to tub and rod will look past rust issues because most of it will be cut away anyway, whereas, restorers will walk away from a similar car. Many years ago, I had the chance to buy a Tucker for $7500. I passed because no one wanted the car and I didn't think they'd ever be that collectable. Do I think a Henry J will ever hit Tucker's status...no...but I do I think that there will be a day where a $6000 J will be a decent buy in the condition described. Just my opinion!