As seen in the super-duper 5th birthday party of 2012, the target game!
The shooter tutorial can be found at Come Together Kids. That is where I originally saw the idea and I won't rip of the concept by making my own tute :)
At most this project will cost you a couple of dollars. At best, it will be free! I always keep a few plastic cups and balloons in the cupboard for when I have a party.
I picked up the clear standard plastic cups and found them strong enough to support the balloons on their own. No need for doubling up the cups.