Easy money
On the island where you start the game, you can go into shops and take money from the boxes on the desks. From the pharmacy (where you get the red syrup), you can repeatedly get 10 Kashes by using the box on the desk, leaving, going back in, and using the box again . You can do this with the basement in the tavern and (if you are prepared to get hurt) the library, where you will get 25 Kashes each time. However, you will have to fight the guard.
Wait outside the tavern on the island where you start and wait for a Rabbibunny to come outside. He should walk over to the plant pot to the right of the door and dig at the ground for a moment. Stand right next to him while he is digging and three Kashes will pop out of the plant. Pick them up and walk around the plant as if you were going to go inside the tavern. Another three Kashes will appear again. Wait for the Rabbibunny to go inside and come out again, then you should be able to repeat this trick.