Real estate closing cost calc

I would like an app built to generate closing costs for a real estate transaction. The underlying calculator is simple addition and multiplication. There are some costs that will be static and other amounts will be entered by the user. Percentages will be calculated based on purchase price. After the total costs are generated I would like the user to have the ability to print or email the total costs to anyone. I have sketched out how I envision the app looking and working but of course I am open to suggestions. I would like the app posted to my web site to be downloaded by real estate agents and others to use for free. I might also like to have something similar added to my website.