You don't need any money at all to do whatever you want, unless what you want to do requires money. This is a silly question. First ask what you want to do, and then see if it costs anything. If it does, then that is how much you need before you can do whatever you want.
And besides, some things that you might want to do require something other than money. True love, for instance, requires that you be a good and desirable person. Or, becoming a successful CEO requires hard work, determination, and the development of numerous complicated skills and abilities.
If all you want to do is mod, then you didn't really have to do much at all 
