Not trying to reinvent the wheel but other car forums do standard things for the "for sale" sections.
Such as:
This is just my $0.02 but I think they're common sense measures.
Such as:
Enforcing new posts to include a location on them so members don't have to click every post to find out if they can even make an offer.
Example: [US-CA] Used Uberturbines x 4 - $2000 or [UK-LON] Tesla M3 Seatcovers - $200 obo
Secondly, there needs to be a rule to post a picture of whatever you're selling with a physical date and your username somewhere in the photo.
It can be a piece of paper as long as it's legible with the current date and your forum name in it. Not typed, not on a screen, but hand written
somewhere to show Proof-of-Ownership. Other forums enforce this so members don't get scammed. We should too.
This is just my $0.02 but I think they're common sense measures.