Prizes for group competitions

[TinyDancer98]

Hey everyone-
I am the philanthropy chair of my sorority and in a few weeks, we will be holding a campus-wide collection race for soda can tabs (our national philanthropy uses them in a recycling program). I'm looking for ideas for a prize. We are inviting all on-campus organizations to participate, so it has to be something that would entice a small or large group of people. Right now we're thinking a sum of money donated to the charity of their choice; the only issue with this is that since it's our first time doing this, we're not sure how successful it will be and we don't want to spend more than we'll actually be raising through the recycling program. I'm looking for any ideas that are fairly low-cost and enticing prizes. Thanks in advance!

[AOEforme]

TKE on our campus is doing something similar: it's a March Madness competition. Half the money raised goes to their charity; the other, to a charity of the winner's choice.