Birthday Party For A 9 Year Old Boy

Hi. I understand COMPLETELY. My sons bday is August 31 and he will be 9. We are having his bday party on Sept. 6th however. I am doing a "Hulk" theme. And thank goodness i bought that stuff...like the plates and stuff....early.. My husband just got laid off. :(
Anyhow, I am going to do it at a park. We have a dollar tree store here, which is saving me mostly. Whew. Lol anyhow, i am also doing some games where kids can win prizes. Such as unscramble words and also a potato sack race...but actually i am just going to tie there legs together. Also i am bought 2 packages of 200 water balloons. Whew....good thing we are going to a park. Lol. So 400 waterballoons...i figure they will love that one. Lol there is no prize for the water balloon fight. Then the 4 th game i am having is: i will have a bag of blown up balloons. I will give each child one. They have to stand in front of their balloon and then when i blow the whistle they have to lay on it with their bellys. The first person to pop their balloon with their tummy wins a prize. The key to this is not to blow them up too much.....that way it is harder to pop. Lol. And the last game i am going to play is at the end of the party...after the cake and everything....i will hand each child a garbage bag....the one who gets the most garbage picked up wins a prize......thats the clean up game lol. Saves me work! ;) anyhow, hope this helps. And if you are looking for present ideas....well, i am getting my child some books and some water toys. Also, i thought about getting him something remote control. ???? not sure on that yet......hope this helped :) have fun!

What kind of prizes are you giving out?
Thanks..