Game money to purchase doughnuts?

HappyGamer73 wrote:
A rough calculation was done a while ago that, by buying and selling bloodmobiles to level up, the cost is about $1M per donut, depending on your multiplier and how many times you've levelled up beyond the max. The number does go up pretty quickly as you level up multiple times, I think.

You're correct, it does go up quickly. I donut farm by buying and selling bloodmobiles as much as I can. My current XP level is somewhere around 2.4 million to max out XP again.

Note that the bat signal decoration gives the same ratio of XP as the bloodmobile. If you want to conserve cash as you are just about to approach max XP, this will help.