My idea is a new in-game item called Admin Verified Seller Badge
This badge has no in-game functions and cannot be equipped or used, similar to a snowball
The purpose of the badge is to prove to people that you are an admin verified membership/zylon coin seller
So when you are going to buy from someone on the admin verified list.. you ask to see their badge. If they cant show it to you.. they are a scammer and you can report them right away. The badge will be untradeable so that it will always stay with that account.
This should effectively eliminate the 'fake being someone on the admin verified list 'scamming which has been pretty bad
So you make a few membership/zylon coin sells.. then you show a staff member. If they can confirm the sales, you are eligible to be added to the admin verified list. First you have to agree that if you are ever found to be account sharing or selling your account, all of your accounts will be banned. This is to prevent the account from changing hands and someone else pretending to be that person and abusing the badge. Then if you agree to those terms, you will sent an admin verified seller badge and once you get it, you can be added to the list.
If you ever don't want to be on the list any longer, you just tell staff and they will remove your badge and name from the list.
How does that sound?