You may want to create a workbook with multiple sheets for various aspects of your budget. You can have one sheet that keeps track of savings and investments and another sheet that lists your monthly bills.
Spreadsheet: A table of rows and columns, free for the entry of data, or formulae for calculating actions on those data. Each row or column is said to contain many 'cells' and these cells serve as 'homes' for every shred of information.
You'll need to include more than a basic level of development and calculation in your spreadsheet. There are lots of free spreadsheets on the web. Most of which are very simple and easy to build. People aren't going to buy a spreadsheet that they can get for free. Take yours to the next level by adding all the value you can imagine. Then research on how you can offer a little bit more on the development and functionality side.
Many spreadsheet applications nowadays have functionality above and beyond the traditional, offering a variety of charts, look-up tables, databases and more functionality than can be mentioned here.
spreadsheet templates for business