Oriental Trading company has a great downloadable carnival booklet. It has a list of coordinators that you'll need, what their duties are, how many volunteers you'll need plus the forms to keep track of what you have so you can see what you still need. They spell it all out.
They also have a calculation of what you need for carnival prizes. They might be generous since that's their business. But here it is -
Based on a 3 hr carnival with about 250 people (you can adust as you need to), for EACH BOOTH you need
375 consolations prizes valued $.03-.07
190 small prizes valued $.08-.16
125 medium prizes valued $.20-.40
65 large prizes valued $.50-1.00
Does anyone have a formula for how many prizes to buy? I think we average about 300-500 people. I am wanting to do a medium for winners and small for losers. I don't think we have budgeted for anything big. So we won't be doing things like stuffed animals or bigger items.