Just communicate in game and then put it up for sale on the market for XXX amount of FG and have him ready with the parameters set to hopefully grab it seconds after you put it up. With that method, you have a *slight* chance of someone taking it but you can avoid that by doing 2 things: 1. putting it up for what it's actually worth or close to it so if someone snipes it then you won't be totally out of luck, or 2. be very very quick about it.
The problem with 1 is that you have to pay the 5% market fee, and the problem with 2 is that you might lose your item and get nothing for it

because whoever buys it is in no way obligated to give it back to you.
The only way to avoid this is to be in the same guild, both have a vault, and have purchased transfer days. Then you can send any items you want (including white items) between each other free of charge
