Average Selling Price _ Now when you calculate your average selling price which is your cost of sales (material + labor) divided by Ƒ_gross profit), you can determine how many customers you would need and then come up with what you think your conversion rate would be for converting leads to customers, you can determine how many leads you would need. Then from this and with the aid of the U.S. Census Bureau and some basic research on your own you can actually have a pretty decent idea of what size your market is and is going to be in the future so you can see if it will support your business plan or not.
If a document needs to be developed that requires input from other disciplines_Finance, HR, Property & Facilities, Marketing, Procurement/Supply Chain_ then most likely you are looking at a team building effort to get the job done. In any event, don't look at the task as only as a roadmap that leads to a profitable product or enterprise. Business plans are a great way to build team buy_in, force a thorough review of options, define objectives, establish benchmarks to judge performance, and help arrive at a plan_of_action. Ultimately, it can lead to a Project Management approach to implementing a plan and that can be as involved and detailed as is necessary.