I'm not sure this forum would be what it is if it was not a good place for knife makers to spend time at. And since they are refining or marketing a product, it seems reasonable to charge them. Since they are making some $ here, it only makes sense that a small portion goes to help running the BBS.
Maybe a compromise is to keep the Vendor classification (w/ yearly fee and their own subforums), and a separate For Sale thread hobbyists can use that requires a % fee of the asking price to go to KF. Then when a hobbyist sells enough, it will be a $ savings for them to 'upgrade' to Vendor status.
My point exactly, it's a free market solution.