Look, haven't we already been through this before?
This is a shit idea & just clogs up the forum with loads of unnecessary posts advertising stuff - some of it being not that great.
There are already loads of Marketplaces online where you can sell your gear quite safely & with proper protection!
Just because someone is a member of a forum, doesn't really make them that reliable does it?
If you're thinking about cheaper prices or getting perfect lenses, then this place isn't going to be that much better than what's already out there - especially if its all done anonymously online & by post.
On the flip side, if you can meet up in person with someone you've met via a forum, then that is a much better solution.
Furthermore, what we should really be doing is trying to organise Anamorphic Groups that can meet up & chew the fat in person!
You know that old fashioned concept of physical human interaction - then a marketplace could develop with reliable witnesses.
As it is, there are too many 1-10 Post advertisers that nobody can vouch for or their equipment.
Also, just because you meet someone [electronically] via a forum doesn't mean you know them or can vouch for them in any meaningful way.
Just my 2 cents worth