Carydragon, the upgrades are free-to-get with ingame money, Kreds only offer those double money and such things. With ingame money you just need the specified level to get the final upgrade, and with Kreds you can instabuy level 31. + Thumb Up Pown187's comment, he saved this game!
80,4% after 17 minutes, it's time to quit as I got the Achievement Addict badge. This game is a legend. Maybe I'll find myself doing all 250 achies someday.