Can someone point me to where the amount of money I have is stored in the save file? Cannot find that.
Search in the save file for your family name, it's rarely used in the save file (your given name is more frequent). Find your own character ("MainChar", a small number, your full name, your age, race, sexual orientation, and so on, all your atttributes and skills).
After your name, age, race and sexual orientation (they're easy to find) there is your home district (two characters, like NW), and after those, there is your money.
If you're new to save-editing, most secure way is to just put some some numbers in between the existing ones, like from 2091.90 -> 2088891.90
This way, less chance to botch your save up. Still, always make a copy of your save before editing it.