1. The Pareto Principle _ Using spreadsheet tracking, you can easily apply the Pareto principle in deciding which of your income sources and expense channels(i.e. products and services sales) to focus on in order to maximize profits. Considering that you are most likely to use the same marketing/sales resources to serve your customers, it only follows that if you focus on your biggest margin selling products/services, you will get increased profits at more or less the same cost.
For instance if a company had five drink brands in the market but notices that Brand A, which has a profit margin of at least twice the others is in greatest demand, they could (a) focus production efforts on that brand, so that more bottles go out to trade (b) Apply Best Practice/Continuous Improvement initiatives that would result in lower costs of producing each bottle of Brand A so that even though the market price remains fixed, the company is able to earn increasing profit margins per bottle.
This last point in my opinion is ONE major benefit you must seek to extract, if you choose to engage the services of a developer. S/he should be able to help you develop (in_house) expertise needed to maintain the application AFTER s/he is gone. If you fail to ensure this, all your cost_savings from using the application might end up being spent paying the developer to maintain the application over time in the future!
In effect what I am saying is that companies which get the most value from spreadsheet automation(including using it to avoid expenditure on less adaptable commercial off the shelf applications) will be those which empower their users to routinely generate "in house" solutions. In such companies, you will find that only when the requirement becomes considerably specialised or complex, does the IT department get called upon to develop or purchase software solutions for user departments or functions with significant data recording and analysis needs.