I've wrestled a bit with the thought. Here are the some of the elements of the dilemma:
A lot of people go to the trouble of registering just to post an ad. You can usually identify them because they have a very small post count, often 1.
We could exclude those people, but what if they're selling something of great interest to our membership? Are we limiting our members' opportunities?
Members can easily see who those folks are and can deal with them as strangers, but careful people can still do business with strangers.
Another dead giveaway is when a poster includes his email address in the ad. Doing so says he doesn't use the message board enough to know how personal messages work and that he can get copies of his personal messages in his email.
As Scott has pointed out, a post count, low or high, is not sufficient to determine the integrity of a buyer or seller. Many people have been involved with the VRCC for years and have a low or no post count. Some have been members for a short while and have post counts in the hundreds.
You can view a poster's profile to see when he or she joined and even list out their posts discovering whether they are all Classified ads.
In a word, I don't think your suggestion is an answer. I think dealing with the VRCC Classifieds in a manner sim ilar to how you would deal with a newspaper's classifieds is advisable. The significant difference is that you may be familiar with a lot of the buyers and sellers here and those with whom you are not familiar are more easily researched than the strangers in your paper's ads.
I'm a member on another forum and once you join you have to post at least 20 post and be a member for 3 months before you can post in the classified. Kinda like it. You can't even see the for sale items until you log in. It's also a free site.
David