Oh, well ,regardless, my answer stays the same. There are pros and cons to the 'For Sale' forum. The only pro I can find is less confusion in user contributions.
Against that is, how often do you see someone selling something in user contributions? Not often. If they were to add a new forum, I'm sure it would be wasted bandwidth that is hardly ever used.

My approach would be, all sales should be on your website, showcase some of them in SC1 and give the link to your site. Bret, or Clone45, did/does this and it worked perfectly.