You'll never have to spend money on the game if you're smart about how you spend your coins and use your available resources. Since the game won't let you roll your device's time forward to shave off construction time, you're going to have to be patient while workers are adding structures to your park. It may be tempting to pay them to work faster, but a better option is to save time-consuming construction for later. Have the workers start on a new structure just before you close the game and leave to do other things, so that the building is completed when you come back the next day. If you are building coasters, make sure to design your own rather than working from preexisting templates, as that will also save you coins. Finally, remember to place as many booths and hotels as your park's guests will happily use, since those structures are one of the best ways to generate revenue.