Who is going to "work out the true value"? The NRL, would you really trust them?
Regardless or who does it it would be rather complicated. For a start some players are "worth" more to one club than they are to another club. The position a player plays in also is a factor in what they are "worth". A simple example, a quality winger would be "worth" more to a club that has 2 third rate wingers, than the same player would be "worth" to a club that already has 1 quality winger and a decent other winger. Ditto for a club that has 2 left wingers a right winger would be worth more to them than to a club that already has 2 right wingers.
There is only one true valuation of what a player is "worth" and that is how much a club will pay them, any club.
Always a Bulldog