A Group for Crowdfunding

I want to create a group where every month we pick a person to crowdfund. The group needs to be seemingly large, and I am thinking of random picking people in the group. Like a bit of a gamble however instead of everyone pitching in money from the get go they fund the person picked at randoms idea. Lets say we all agree to a max of ten dollars each. and if the group is at least 100 strong that translates to 1000 dollars. Larger group = larger payout.