To me, the idea of this site is to learn from fellow members, help others when possible, and contribute to the general "pool" of knowledge on this site for future questions people may have. Many people on here sell or offer services to fellow GJ'ers for big discounts, that they would never dream of giving some random person off CL or Ebay. It's a bit of a brotherhood (and sisters too!). I've given away stuff to fellow GJ'ers for free, including shipping in hopes to just make their day, and have them pay it forward. I've also been offered things for sale for pennies on the dollar here, compared to what the seller could make on it on Ebay. That's what makes this place great.
I remember recently, a member posted a link to an add on CL of a tool box a guy was selling, and pointing to the same guy, selling the same box here on GJ with only 2-3 (can't remember exactly) posts, and was a new-join. He was asking like $600-700 bucks MORE on GJ than on CL. That's a complete 180 from the spirit of this place. That's not even taking into consideration the scammer type issues. Anyone can scam, whether you have 2 posts or 20,000. But people who have spent the time and become invested in this community are less prone to be the ones that stab fellow members in the back.
The issue does come up with alienating the long-time members that have low post counts. Unfortunately, there really isn't any perfect way to go about this, but I think implementing a minimum post count is one of the better methods of this.
I'm uncertain of what the forum host will allow Ryan (or whoever) to be able to do, but I know of some forums that have a "Rep" system, where people who have done business with fellow members can give them a "Rep" or thumbs up. Even relatively new members with 3-4 reps from known "veteran" members show they have held up to their word a few times already, and it helps speak for their character.
I think if that was a possibility, it'd be a good addition/suppliment to the 100 post rule. "100 posts or 3+ reps" or whatever.
Just a thought. I do support the idea of making it a bit harder for people to just join GJ to post **** for sale, CL and Ebay is right there for that.