Firstly, if you want to collect some money charge a nominal fee, like $5 per war or maybe like $20 monthly membership. To get more people invite friends to join. Tell them to tell their friends to join too.
In a thread from last month, Shmmee commented about a Wyoming nerf group that registered as a non-profit.
You might see some unexpected doors opening if you register as a non-profit. If local businesses donate anything to your group they'll be able to write off the expenses on their tax forms. Theirs a wyoming nerf group that has really taken off recently and since they've registered as a non-profit they've had several buisnesses donating everything from gift cards to by ammo to NIB blasters. They've also seen tremendous support from their counties parks department in the form of free venues to nerf in. You'll also be able to get group insurance on the cheap.
You may wish to look into this.