They should have a sub forum, and users should be able to post there. From the interactions Ive had with people, here is how they use the B/S/T section:
1)Click Buy / Sell / Trade
2)Scroll past all the stickies.
3)look at user's threads
You literally can not see the first user post if your resolution is at 1920x1080 or lower (standard HD) without scrolling down. The screenshot attached is after I already scrolled down to put the first stickied at the top of the screen. I'm not advocating removing the vendors or hiding them anywhere, just putting them into their own section where they belong. I say give it a whirl, and if NON VENDORS ---smurfette--- and moan, change it back and I'll never bring it up again.