On another forum I frequent there is a 7-month waiting period before you can post in the "For Sale" forum. I thought this would be a good idea based on the amount of threads I've been seeing lately in the Parts for Sale subforum created by new users that go nowhere - people respond and the person never comes back to the thread. Of course there's also the much worse circumstance where money changes hands and the buyer never gets their item or gets an item in poor condition - not sure how often this happens.