Previously, you could only get a special balloon as a reward for a Marathon of Festivals, but now you can purchase a balloon decoration for your own diamonds.

In order to see which balloons are currently available, go to your township -> click on the festival building

Choose the "Festival" tab and click on the balloon of your township.

You will see a new button "Balloons", click on it and choose the balloon which you like the most.

Balloons are expensive because it took a lot of efforts for other townships to earn balloons during the Marathons. After all, the more difficult it is to obtain an item, the higher its value.