Sam I don't know about the collectors forum, but the way it reads on the "Become a Sponsor Link" at the top of each forum if you are selling newly made items you would need to become either a regular sponsor or an Associate sponsor. The way I understand it the classifieds are for used merchandise. Below is a description of the types of Tradgang sponsors:
If you are running a business that is related to Trad Bowhunting and have a web page that promotes and supports your business then the Full Sponsorship would be required. Full Sponsors are also eligible to purchase ad banners.
...Associate Sponsorship information: If you make or craft items yourself that are related to Trad Bowhunting or have items from time to time (staves, bow socks, etc) then you would likely be qualified as an Associate Sponsor.
...Corporate Sponsorship information: If your business is not related to Trad Bowhunting but would like to sponsor the site and have your business name recognized on a list of Corporate Sponsors, then we also offer this type of sponsorship as well.
...Contributing Member information: If you as a member would like to support the site individually all it takes is a small contribution to do so.