The idea (by what I understand it) is that if you have been a member long enough to post 50 times, you will have been here long enough to "Earn" the right to buy & sell on our forum. It helps to keep anyone from joining to just make a "quick sale" and then run. If you're dedicated enough to the forum to abide by the rules, then you should be dedicated to the hobby.
If you want to make a quick sale, go to Ebay or Craigslist!!
- RCT