Chef Job in Cedar Grove, New Jersey

I'm preparing for my husband's 75th birthday BBQ at my sister-in-law's home in Cedar Grove next Saturday, July 15th - starting at 4pm. We expect 30 guests, have rented a tent set-up and a 5'x2' charcoal grill. We don't need catering, as such - my son is preparing ribs, another guest is preparing chicken, and I'd like to grill a butterflied leg of lamb, corn, and other grilled vegetables. I'd like to know what you'd charge for 3-4 hours of manning the grill so the rest of us can enjoy the party.