Biggest problem Admins have is we have lives to lead. Selling issues whether it be selling fake stickers, disputes, advertising without sponsorship, etc, take up a large proportion of our time on the forum. I think any method that requires more admin interaction, instead of less probably isn't the way to go.
My biggest concerns are trying to understand why somebody needs to sell more than a couple of times a year. Surely if you buy to use the kit then it's more of a one off sale or a season end sale? Occasionally you get something that doesn't fit but some of the constant trading from members concerns me. Noted one guy has opened 13 sale topics since Jan. I'm also concerned about the amount of new or nearly new kit coming onto the forum. You spend £150-200 and then immediately sell it? Again, I can't quite get my head around it.
Some people just like buying kit but sometimes these things need to be reigned in. Ebay is the appropriate marketplace if you want to trade kit.