I think that the NBL really, to survive and thrive has to allow big markets to spend big. Yes it would mean that the regional teams would find it harder to beat the big cities, but from a spectator view it is necessary to create the spectacle and excitement.
If I was in charge, I would obviously get rid of the point system, and only cap 8 of the 10 players. So a marquee local and marquee important can be outside the cap. The other 8 players would be under the million dollar cap.
This keeps some regulation but would allow the bigger markets to chase some of the bigger names out there, and get some interest back in the comp.