That's about a quarter of your working time you won't be reimbursed for. You may end up being able to work and sell more hours. But don't count on it. If you don't base your calculations on a sane, reality-oriented set of assumptions, you're looking for trouble, burnout, or other unexciting forms of life stress. For this article, let's use the 1,200 number.
Many consultants get far more.
Obviously, there's a lot of leeway in this figure. For example, you may have minimal business expenses, defer socking away that retirement money, be willing to draw a much lower salary, or find and work more billable hours. Like I said, this exercise is very informative. Don't apologize for your prices, if they're fair. This is the cost of your business or service, and includes all your overhead.