I see you are in Corning so that means that you will probably have to drive to Chico to shop or use the local supermarket. Driving time, mileage all add to the cost of doing business. I suggest you have a min. price no matter how small the job. $15 is way too cheap for your menu since you have brisket and ribs which are the most expensive meats in a typical bbq menu. If this was a larger group of over 50 then the price would need to be at least $18 p/p, when you are playing in the smaller groups you can't compete with the restaurants so I don't try. Define your niche and stay within that for success. I cook on-site, my min. is 50 and soon to be 75 and my min. price is $15 for chicken and two sides. Good luck, you are in a small town so you may have to adjust my numbers and you may have to drop off and not do a buffet line in order to keep your prices low. It is way too much work to run a catering operation as a hobby so operate like a business. There is satisfaction when people like our food and it makes you feel good but it feels even better then you also deposit your profit.