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.
I often see people split into two camps. On one hand those who almost ignore competitors in their business plan, because they do not want to think about the issue yet and feel so confident they have a great idea for the market regardless. But I recommend not being overconfident when it comes to competitors. They are still there for a reason, they are still around and in business for a reason, so view them with that in mind.