You'll need to develop good marketing material. Things like demo videos, which you can find plenty examples on YouTube, screenshots, and keyword rich descriptive text help people find your spreadsheet and communicate the value that sets yours a level above the rest. Excelville.com actually allows you to upload your spreadsheet with all of this marketing material in an easily searchable and user friendly website.
You could make money doing something you love (or like [or maybe not so much but just really good at]). It's great to see a spreadsheet come together, and usually a lot better than what you originally envisioned. Especially when the dang thing works.
Early databases available for the PC market were simple two-dimensional solutions and were essentially designed as a record-keeping system. However, when computing power increased, the advent of the relational database became an affordable option. Applying the rules proposed by Edgar Codd, the Database Management System (DBMS) became a reality, with products such as dBase being widely implemented in the desktop market.
Apart from these very popular categories, business owners can find various other types of spreadsheets solutions by collaborating with a prominent, reliable spreadsheet-solution-providing company and opt for the 'Personalized Spreadsheet'; solutions that are especially designed to meet your imposed criteria, created from scratch, tailor-made and adapted to your particular needs.