Fill a coral with about 60 slimes, add an auto feeder. Make sure that it's filled with the slime's favorite food! Set the speed for the auto feeder to fastest! There! That should give you about 600 - 1200 newbucks a day!
The 'Wilds' update has a new biome: The Wilds! Search deep in the Wilds where Sabertooth Slimes live! Then keep looking for the HANDLEBAR MOUSTACHE!! (Put it on your slime!)