Multiple meat quantities.

I have been catering for three years now and something that still confuses me as how to get my pricing lower is how much of each meat to provide when catering multiple meats. In the past I have been figuring my prices say for pork and brisket on 4oz of each meat. The problem I am having is that by doing so my prices are coming in much higher than other caterers. For instance my competition does pork and 2 sides for $10 and for $1 they do pork and brisket. I am paying $2.89lb for brisket x2 once cooked $5.78 so a 4oz serving costs me $1.44. So how do they charge $1 for something that costs more unless they are providing say enough brisket to fee half the people but then the cost is still $0.72 per person and by charging a $1 they are making nothing for the 2nd meat. What am I missing? Is it considered ok to run out of one meat so long as you don't run out of both?