I was part of a small group that did this a few years ago.
Basically you would PM the guy who was coordinating it. He would send out a message to the other members with "1 member is selling at $4.35".
It ended up only about 2 or 3 of us other than the coordinator. And it was not very useful.
thanks for the input,
1) how many did the group start with
2) why the PMs
3) what was the performance track record
1. started with 1 or 2 people :/
2. The PMs were so that people could stay anonymous other than the guy running it.
3. Performance was inconsequential.