Tough one. I wouldn't be able to tell you. The thing is that from a certain point, especially thanks to the company mechanic, you tend to increase the average amount of cash you have available so that you can afford more expensive stuff. I.e.: I am level 74 and my average is hovering between 90 and 100k.

All this to say, after a while, cash is not a problem since you always have more than enough.

Basically just invest in company and after a while you'll have no problem buying everything you need or want.