Hi,
Normally your local paintball field will have rental guns available. If not, just play in smaller groups with people sharing markers when they aren't playing. For example:40 people who have 20 guns can play 2 ten person teams while the other 20 sit out. As far as paint goes, just have everyone chip in some cash. Sponsorships would be great, but with today's economy, you would really have to sell the idea to get any cash or equipment. We are having a FD league at my local field this year and I am really looking forward to it. I don't play, but I do take pictures that aren't too shabby. There is a post by Bill in the comments sections of this group, he might have some more ideas for you. I hope you can get some teams together.