This is a radical suggestion but bear with me because I think it solves a number of problems that the game has now. It will undoubtably need some tweaking especially with the specific formula.
Problems:
* Players are too cheap in general
* The best players are cheaper than medium skill players
* New teams buy players that are too expensive, go broke and draw the conclusion stupid game and quit
* The truly elite NT level players, the Kobes, Lebrons, Roses and Howards are close to worthless: For example the BEST big man on the Australian NT Keith Anderson (22818997) has been recently sold for $70,900. He is 25, HoF potential yet no-one wants him.
* Players can STILL easily load up their team with rentals for big cup matches, playoffs and relegation series they just need to get them before the Friday and train GS
Solution
Make the minimum price you can list any player at 10 times their weekly salary.
This will have a dramatic short term effect of causing a mass retirement of older mono-skilled players that no-one wants. Then the price of players will dramatically increase. The market will be a big mess for a bit while the adjustment is in progress. Maybe there could be a $1,000,000 maximum just like with free agents.
It is simple, elegant, already in place for free agents and solves five massive problems.