Some tips for some superquick cash:
On day 27 with 6 Kongpanions and 28.9% upgrades, I managed to collect 1.3M+ coins in one run. 2.2k coins were flying at my armadillo in masses. I went 100k feet.
My upgrades were (2, 12, 8, 18, 5, 4, 8, 5, 14) with Kongpanions.
Once you get the ones for (in my case) +6 magnet, (2x)+6 Total Objects, and (2x)+4 Coin Bonus, follow the coin trail down low and occasionally use your rocket to speed up. I generally tried to stay at 20ish (speed units?), because going too fast ruins your coin magnet radius.
BE CAREFUL NOT TO HIT ANYTHING WHEN YOU ARE GLIDING/ROCKETING.
Power Generators and Launch Power do great things for your initial launch!
UNLIMITED STAT GLITCH - Put all of your Charms into your stash. Repeatedly open and close stash. The Charm bonus(es) should now be applied multiple times.
Ehhh.... A little easy... too easy.
I beat the final "boss" in 6 hits and didn't even get hit myself.
It's very slow game and very time-consuming. The plot is very simple and the game itself is very repetitive.