What you pay multiplied by the number of Members is (hopefully) what the aircraft is worth.
[pedant] What you pay multiplied by the number of members is (hopefully) what the aircraft and any spares holdings and any accumulated cash (e.g engine fund) or other assets is worth. [/pedant]
A one fifth share in aircraft with a 5k engine fund is worth 1000 quid more than a fifth share in the same a/c with no engine fund.
Mike