Hey Rick!
First of all, thats a good idea.
We had the same in the e90-forum and there we created a thread only for sales at the meeting.
HERE is the link.
I think the best way is to write down all the stuff you want to sell in a list (like in the link) and then somebody contact the owner and start trading
I hope i wrote it understandable
But it is also ok if you bring the stuff you want to sell to the meeting, because the thread is german and you are not registered.
So ... take your parts, etc. to the meeting
What do you think?