@Isaac,
I wouldn't want the NBL having to administrate and attempt to keep transparent a system quite that complex.
You're probably not going to get much success convincing clubs to buy into naked revenue sharing, so allowing clubs to "buy" points might be the best bet.
Okay, I'm just going to throw some off-the-cuff ideas about, so everyone be gentle if you think they're stupid, this is just a back-of-envelope idea. The important thing is to make it attractive to both clubs looking for that extra little bit of effectiveness without being potentially ruinous, and to clubs which we would consider have nots; make the rewards to them from the system sufficiently juicy to accept the imbalance.
With a nominal salary cap of $1,000,000 and 70 player points, we get about $14.3k per point. You could allow a team to purchase a point, which comes with the attendant $14.3k salary extension. Tax gets paid to a distribution fund which goes to either clubs that are designated as poor, or the bottom four, or else those clubs below 90% of the cap. Now this could be employed to either stop the axing of players because of one point here or there not fitting into the point jigsaw puzzle, or maybe to sign an additional player. If done as a mid-season sort of injury signing, the tax would be paid into next year's fund.
Make the first 3 points cost a 1 for 1 tax, the next 3 a 2 for 1 tax, and the next 4 at an exorbitant 3 for 1 tax, and prohibit any further than that (10pts, since that is what the player points taps out at).
Ergo, if you want an extra 1pt player, or you want to retain a player who has had their points changed and the points just won't quite work out, you pay $14,300 tax, get 70+1 points and the $14.3k salary exemption.
If you want to sign a college returnee on the 3pt standard, you have to pay $42,900 tax to distribute to other clubs. Include using the extra salary to pay the player and it costs the taxed club about $86k all up, and nets the bottom four clubs an additional $10k each to attract that extra notch of quality on their import.
If you want to sign a Greg Hire type 6-pt player over the cap, you face $128k tax, the weak clubs are abruptly much closer to the normal salary cap. Taxed club is paying $128k tax+$85k salary, gets a boost, but a Greg Hire type player here or there is not going to break the league.
If you want to go whole hog, sign something like a naturalised import, a la Redhage, outside of the cap, a 10 point player, you pay $42k + $84k + $171k = $300k tax. You pay $300k to the league, all the weak clubs chew up half the distance between their spend and the cap, you can pay up $143k to the player for a total cost of $443k, whatever benefit you gain from signing a potential crowd pleaser should be offset by the league-wide benefits of weak clubs having an extra $75k to throw at their import signings and you have a balance between benefit cost to club and league.
The have clubs could handle those sorts of costs, the have-nots could use the tax returns to increase the overall competitiveness of the league and we'd have a few more showtime type players running around.
Again, this was just a couple minutes of my lunch break spent with a calculator, so if everyone thinks the idea is stupid, no sweat, but it's good to have ideas floating around.