I agree with everybody that have posted.
The idea to use USPS and a USPS money order is also a good one. So is the idea of PayPal.
So, restricting new members from selling anything unless they have 50 posts and three months time on the forum are also good ideas. I know that the 'Quack Shack' requires this. They also have a feedback column for both the buyer and seller and must submit a feedback response. Additionally, they also insist upon a communication of PM's and statements made of the item for sale thread. I bought a Texas Star 350DX amp and that is what I had to do. I think that it worked out fine. They also had a protocol for the seller to post pictures, statement of electrical condition rating from 1-10 - and also rating the physical condition from 1-10. The item ad must then be approved by the moderators, and is also monitored until the sale is complete and all feedback is in place. Then, they lock the thread as complete.
Seems like a lot for the moderators to do. But since this site is also selling things frm a shop, this may be the best thing to do. This isn't eBay or the Quack Shack; but it wouldn't hurt to make it work like that to a degree. Making it harder for slimy dealers who have wiggled their way in and deal garbage of an outright scam. Using/borrowing ideas from other sites makes it more conductive for deals to happen. It will also increase sales and boost seller/buyer confidence - which is really the bottom line.
Sure, you will always have somebody who will try to take advantage of the system - but with NOTHING in the way of protection and accounting in place, it makes it too easy for slimy dealers too take advantage of WWRF memebers.