When you're writing a business plan in a situation like these, you need to address a few issues the intentional entrepreneur has already pondered. The first is do you really want this idea to become a full_blown business? Certainly it's flattering when you realize there's a market value for something you were doing anyway, but that doesn't always mean you should launch a business. A lot of accidental businesses form around fads or seasonal items, and may not be robust enough to function as year_round, money_making, enterprises.
Now, in addition, when you know the average number of transactions per customer and you know your average dollar sale per transaction, you can also project how many customers you would need over those 10 years as well. This would tell you everything about what your business would need to do to give you the salary you want. So, wouldn't it be nice to see what a plan like this would look like? Could you do it? It might not be as tough as you might think.