brisket is time consuming to cook---pulled pork is not as bad----but time is time
Are you using your BBQ pit? Are you supplying the fuel for the BBQ pit--charcoal, wood, etc cost money.
How many miles will you be putting on your vehicle, and how many hours of work---these hours include shopping, prepping, transporting, cooking, slicing , serving and clean up.
Chances are if you quote what this job is worth---they will balk at the price. It is hard to divide the cost among 50 people---they will think that the cost per person is too high. However cooking for 200 people is not much more work---not much more time and more people to spread out the cost.
Estimate your total hours----determine what your time is worth per hour----add in a BBQ rental fee---if you didn't supply the pit, they would have to rent one. Charge for fuel, firewood, charcoal, sterno or anything else you use.
Even if you charge minimum wage----quoting for only 50 people causes people to look at you funny----they do not realize the time and costs that you are working with.