First things first. Find a foodservice distributor locally that can answer your cost questions. If you work in a restaurant, ask the chef/manager to see his/her weekly order guides/usage reports to see what costs are.
Foodservice distributors are happy to help, that's what they are there for. I wouldn't rely on what Joe Blow in Wherever, USA says he spends on mozzarella to build a business plan. Get detailed, specific, accurate info from your local market for your basis. Otherwise you will end up another negative statistic.