These are the pros and cons of selling spreadsheets. The real beauty in this idea is that you could do the work once and there is no limit to how much you can earn, especially with effective use of the internet and other mass communication tools.
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 find a way to make your spreadsheet accessible. You can build a website, which will require paying for a domain, hosting, site security, dealing with an internet transaction service, graphic design, content for the website, marketing your website, Search Engine Optimization, and all the other madness that comes with managing a site.
spreadsheet templates for tracking
examples of spreadsheet packages
spreadsheet templates for business