Our group rules state that the seller must first offer his share back to the group for first refusal. Following this it can be advertised on the open market, the only time a que develops is when more than one share becomes available for disposal. The first in line then gets priority but if say an aquaintance of seller number 2 decides to buy his share then that is just the way it is.
You looking for a share in a C172 at Barton Tiggermoth? If so, PM me.
Regards
SRD