Worked out what the negative number is. When you buy wheel force upgrades it charges you the cost of the next upgrade, not the one you clicked on. So 1200 charges when you click the first one. PS love the animations of the guy running in it!
Thanks to you Timps, I was able to fixe the bug and the spin animation. It will be available in the next update but I can't upload it before the end of the Jam voting.
