For 2,500 square feet the build out will cost you $2,250,000. (Remember these are just theoretical numbers, for a high-end place.) For your space, take improvement and upgrades you intend to make and divide by the total square footage. A restaurant designer that is going to cost you about $45K. 2  A public relations firm that is going to cost you $25K in the first year. 3  A lawyer to put together your partnership and operating agreements.