I really like the idea of salaries based on transfer prices. A way to implement it might be to have two components of salary
component 1: the regular BB salary
component 2: the transfer portion
The transfer portion could be zero until someone pays over a certain amount - like 2 million for instance.
Also, if a player is playing more than 48 minutes a week in division I, then his transfer salary could gradually increase to the average of the starter's transfer salary in that division.
Just an idea.
Run of the Mill Canadian Manager