Salary cap

points system would work like the SC but rather than money, there would be points allocated to players when they were signed

It was first proposed in Australia like this

Each player would be assigned a simple points value based on how many first grade games they have played and if they have played rep footy and then clubs would have to keep under a nominal cap figure.
I haven’t done the detailed maths yet and some work would have to be done to make sure the numbers added up but it would work something like this:
Each club is given 120 points for their top 25 or 30 players. Players are worth the following:
Yet to debut: 0 points
1 – 50 games: 1 point
50 – 100 games: 2 points
100 – 150 games: 3 points
150 – 200 games: 4 points
200 – 250 games: 5 points
250 + games: 6 points
Current (last two years) Origin or international players (from Australia, New Zealand or England) would add five points to their value. I wouldn’t include other international football so clubs don’t ask their players not to play to avoid boosting their cap value. Most of the players that play for Fiji, Samoa, Tonga and so on would not make a top-tier rep team.
There would also be discounts available for the following:
• Player made their debut at their current club: minus one point
• Player has played 100 games at one club: minus one point
• Player has played 200 games at one club : minus two points
• Played 200 + games at NRL level: minus one point
• Player has played 300 + games at NRL level: minus two points
So a player like Cameron Smith would have a base points value of 11 points. For another club to sign him he would be worth nine points and to the Storm he would only register as six points.
Similarly, Paul Gallen would have a base value of 11 points and if another club wanted to sign him they would only get the one point discount. However, if Cronulla want to re-sign him, it only costs them seven points. And they might only pay him a base of $300k and find the rest in sponsorship as the most visible face of their club.
The idea of the points system is that it rewards loyalty and player development. If a club goes over the points cap in a season because three or four players made rep debuts or clocked up more club games that is ok. They can stay over, but just can’t sign any new players until they come back under the points cap.

With a few tweaks its a decent idea.

However personally i think you could do it much simpler by simply restricting the squad make up by saying your squad of say 30 (i think squads are a little small at the moment) and saying you have to include at least 15 with you before their 19th birthday, no more than 5 from overseas and no more than 7 who have played for another SL side you could achieve the same thing.