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.
The spreadsheet templates used for business purpose are also complex and these templates are used in stores and other business related affiliates. Profit and loss are mostly dealt with these spreadsheets. Invoice and other deposit related calculations also can be dealt with these spreadsheets.
Over time, the spreadsheet grew into what we see today, in the form of Microsoft Excel and a number of similar products on the market. The power of the spreadsheet has grown almost exponentially, allowing the user to create customised formulae, charts, pivots and so on. Worksheets can be linked and updated automatically.
Undoubtedly, spreadsheets can help you improve the efficiency of your company regardless of the nature or size of your business. However, it is very important to note that the process of programming formulae and mathematical algorithms behind spreadsheet programs can be very complex and time consuming; one having to invest much effort to create the most appropriate spreadsheet solution for one's company.