Probably need 30-ish pounds of cooked meat. What do you pay per pount? You'll need to by close to 60 pounds of pork for this. I'll use a rough price of $1.29/lb, but this could and probably will be different based on what you are paying. That's a cost of about $78.
Then you have your rub, fuel, any sauce, foil, etc. For me, cooking 6ish butts, I'd estimate that at another $40 (may be high, but I don't use cheap charcoal, and I don't want to sell myself short). Therefore, you're at $120 cost on your pork.
Figure out how much your beans will cost based on your recipe. Because there's only one side, I'd say either a full hotel pan and a half, or 2 whole ones. Add this amount to your pork cost.
How much are your rolls? Add that in too.
Are you providing plates/plasticware? Don't forget that cost.
Then, how much is your time worth? General rule of thumb is cost X 3 = price. If you're not a business, and you are ok doing it for less, fine.
Me? I'd probably $7/head out of it.
