How about a minimum post level and/or membership time requirement for posting in the marketplace?
Just noticed a 1-post May-2012 posting a link to his seat covers on Craigslist
No price, no photos... obviously didn't read the rules.
We've got a bit of a "brotherhood" and it's nice to feel that when we're dealing with someone in BST that we are dealing with a member of the community.
Most forums do have minimums, even for buying.