Well, the waiting list has not worked for me, YET.  However, I do think it is a good idea.  
Things happen, you get an extra copy, trade, or are done collecting.  A friend of mine, who is a huge collector, recently decided he wants to get rid of a lot of stuff, which boggles my mind.  In my current state of mind, I would never sell anything, unless I had a double.
I just figure, it is better to sell a copy to someone on here, for the insane amount they go for, to another member, rather than at the same price to some d-bag on ebay.