I'm not the beast at making cash, nor am I the worst, but hopefully in the guide I shall explain to you how to make quick cash for when you need it. The best way to make cash is to go to either ::train, or ::train3. Once there just simply kill the barbarians. I'd recommend going to ::train because there's more barbarians there. Eventually after killing the barbarians they should drop red party hats. Once you've collected you're red party hats just go to shops, trade the clerk, and sell them for 100,000,000 coins ( 100m ) each. I hope this guide helps you!
This is the best way to make quick cash that I'm currently aware of. If there is a better way I apologise, and I'd also be glad to know what it is.
$ $ $ $