bizznessman hit a lot of nails on the head, and 100/hr isn't unreasonable to charge someone, my mechanic gets 125. CONTRACT!!!! However, he left one huge part of the calculation out. Food cost. To do $5000 in sales, assuming 1/3 costs, 1/3 meat, 1/3 her, 1/3 you, you're looking at about $1600-1700 in food costs. Jesus, please, get a contract. I had the same arrangement when I started out with my local butcher. I was making bacon at the time. hindsight is 20/20, good people turned out to be bad people and I never saw a dime. My arrangement was the same as you're initially proposing. However, tread lightly. First off, to do $5000 in sales of bbq in a weekend you're going to need about 400lbs of raw meat. How do I come up with that?
Lets say you're getting $20/lb for bbq. To do $5000 in sales, you'll need to sell 250lbs of product. To get 250lbs of finished product, you need to start with almost double due to cooking losses.
So lets be more realistic, you sell about 100lbs of bbq in a weekend, presumably $2000 in sales. That 100lbs of finished que. probably cost between $400-600 just for the raw product.
now add in expenses, I don't know what kind of smoker you're running, but I can presume you'll need at least 40-50lbs of charcoal to cook all that food, or at least a bag of pellets.
tack on another $50 for wood and fuel
Rub, rubbing close to 200lbs of meat takes some product, tack on another $20 for rub.
So for arguments sake, there's around $800 in expense. If you do $2000 in sales, you're looking at $600 for your profit for the weekend, and that's assuming you have a sell out, nothing left but maybe scraps weekend.
Now, the questions.
Who's serving the product?
Is she willing to take the risk of buying cases of meat?
What happens if you're sitting on a ton of unused product?
Who will be there representing your product and brand?
Will you get to book your own catering out of clients, or will they have to be sold thru the butcher?
Why are you willing to promote this lady's business over yours?
How will you be accounting for the sales of your bbq vs. her food? IE, cold salads and other sides that people may buy when they're purchasing your meat also.
With all that said, unless you know this person, WELL. Unless you have a strong contract clearly outlining, run away. If she really wants to add bbq to the menu, tell her you'll work for a reduced rate of $50/hr.