This could be a nice addition to the finance tab.

Let's say the season has just ended and you have a star player who's been smashing in goals and has really solidified himself as your club's talisman. At the start of next season you can choose to invest money worth 50% of that player's market value into merchandising and selling shirts with that players name on it (provided you've built the utilities part of your stadium too maybe).

This will generate revenue for your club proportional to his performance in games. Stuff like number of appearances, average rating, number of goals, number of assists, man of the match, being first in the league, ect.

Additionally I suggest that past certain milestones of generated revenue, maybe the game rewards you tokens/packs.