How is bonus money collected in The Last of Us?
Solution 1:
The money is gained by completing challenges. You should be able to find them under Bonuses -> Tags in the menu system. You collect money (amount of which varies with challenge it seems) for every challenge completed. Some of the challenges are associated with trophies, but the money you earn from that is not linked to any trophies, neither are the unlockables that you purchase with the money you've earned.