Hi there Stamp...
There is a new feature in EU
since you left, and the Friends list thing has been upgraded a little. Now, when you are in game and push J you see a list of your friends as usual... But you can also do a lookup in the player register for players you know the names of.
The joy of this feature is that you can find people who are not stood right in front of you at last, and see if they are online, and send a friend request etc.
My personal experience is that you still need to log off and back on after they accept in order for them to appear correctly in your friends list (but maybe it works first time for you, who knows?)
In short though - you should be able to find the buyer on your own and see as soon as he is online etc, in future.
Good luck out there, and welcome back!