Great thread guys, alot of really good ideas here.
This is my take on the subject from the prespective of my primary character Amp-Rage.
Stipend. As a licensed card carring Hero of Paragon city we are an extension of the city law enforcement and therefore receive a salary.
Bonus. Anytime we arrest crimals or complete missions we receive Influence. This could be looked at as an additional subsidy or possibly hazard pay. For example......Say you bust a drug lab that was manufacturing Superdrine. As part of the bust $1,000,000 in drug money was confiscated. If 99% of that money when to the city and only 1% to the hero as a bonus or hazard pay that would still be a $10,000 dollar bonus.
Gratuity. When we save someone they often give Inf as well as praise. This one I have a bit of a problem with as my instinct would be to turn it down. Since we are not given that option in game the best I can come up with is that maybe the 1st few times I tried to turn it down, and they became upset because I was trowning this gift back in their face. So I just deal with it.
Finally as a mutant and member of G.I.F.T it would stand to reason that I would participate in medical reserch on genetic mutation.
So between Stipend, Bonus, Gratuity and reserch pay I can easily explane the 2+ million Inf in my account. Which would allow me to concentrate on being a hero full time. Thanks.
Amp-Rage lvl 37 elect/elect Blaster

Protector