Games, balloons, and bright colors -- a carnival is just like a birthday party, but better! So why not invite kids to a carnival-themed party in your backyard or at a local park? Any supplies you don't already have at home are inexpensive and easy to find. For the booths, raid your linen closet for colorful sheets and lightweight blankets; hang them from ropes or clotheslines suspended between trees.
If trees are scarce, stick volleyball or tent poles in the ground (in a public place, check with officials first). Older siblings can don utility aprons and man the booths, or you might ask a few of the other parents to help. At day's end, each child will leave with souvenirs and memories of a great day at the fair.