The Fun Stuff section of the Shop sells Fun Buildings, which are a great way to earn !
The Selling Price is always very minimal compared to the purchase price.
Any building that costs acorns only sells for 5 .
You may also wish to keep in mind that the Movie Theater functions in a similar way to fun buildings. It's earning rate per minute is 1.01, for comparison.
What are the "Best" Buildings to Buy?
Answer: it depends! If you play a lot, you may be better off getting a lot of Mud Spas (which are cheap, too!), since they recharge in 30 seconds. If you surround them with enough palm trees, they can give you ~500 every 30 seconds for every spa. If you only visit your game once or twice a day, you will probably be better off getting several fun buildings that recharge after several hours but give you a higher payout (again, use lots of decorations around them to increase the payout). See the Layouts page for money-making strategies using decoration bonuses.