Question has been answered, I am going to move this thread to the archive, if you have any other questions OP, feel free to make a new thread.Between Pac Std glitch on repeat, the CEO and VIP solo/paired grinds, and the double $ modes, theres a fair amount of ways to earn right now. I wrote up a bit about this last night, along with at least one other contributor who did the same, it should still be close to the top of the support main page, in response to a similar posting. I also have found that selling off some of my older cars that have lost their "new hotness" is a quick way to bank a little money and free up some garage slots at the same time. (2 more new ones coming pretty soon, at least!)
As to upgrading the Proto, dont quote me, but i think i probably dropped another 175-225k, maybe? Its not bad, there arent a lot of super expensive options really. Standard upgrade costs for top tier performance stuff, then dependant on your tastes for the asthetics. Its not horrible though.