A decent stock Henry J commands a higher price nowadays than ever before which always surprises me when you consider what you're getting. They're good cars but options / accessories are often scarce and for as much as I like them, I have to admit they do not ride like a full size Kaiser or Frazer. All that being said, they are unique, fun to drive, easy to work on and mechanical parts are fairly easy to find.
What's one worth? I get that question all the time and I really don't have a good answer for it other than "whatever someone who wants one is willing and able to pay..."
I saw a pretty decent four cylinder model sell on ebay a couple of years ago for $11,500. It was not completely original and it didn't have a lot of options if I remember correctly... I recall it did have a trunk lid.
There was one that sold at Barret-Jackson a couple of years ago, six cylinder without OD and it brought $30,000 or thereabouts! Clearly an outlier. Alan Thomas got $13,500 for his '51 back in 2005 (sold on ebay). It was all decked out with factory accessories and had very nice original red dinosaur vinyl upholstery in it.