I finally got in touch with the Treestand Manufacturers Association and the guy there said they sell between 1M and 1.5M per year. That is a huge number and way more than I would have expected. He did not know how it broke down betwen climbers, ladders, hang-on, etc.
He was not too hopeful of the prospects of trying to sell treestands as the insurance almost makes it prohibitive. He said it was from $100k to $1M per year depending on the size of the company.
Not that anyone was interested in this stuff but --- now you know.
Cheers,
James