Well good thing you came to the one place where we handle stuff like this on a daily basis.....
This is why everyone is trying to help you and give advice.
It's really not that complicated and at some point you have to take a leap of faith.

1- Take picture of back of coin (hologram) side with a name and date paper
2- Post up an auction in this section of the forum
3- Winner sends escrow funds, You send winner coin
4- Winner reports that coin received in good standing and escrow is released.
5- Everyone is happy