This article is meant for those individuals/businesses who sometimes experience a need to use their spreadsheets in the (somewhat "impersonal"?) manner described above, to get the results they want. That need would often arise out of their lack of requisite skills to get the spreadsheet to behave the way they want _ or limited time to devote towards incorporating necessary automation to make it do so.
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!
The savings _ from using your "in house" expertise _ in terms of money and man_hours alone, will quickly justify the investment you make in "developing the needed skills" _ especially, when you compare what you spend with the cost of purchasing a commercial software application _ or even engaging the services of an Excel VB developer.
Variable Costs Control/Reduction was a strategy that worked extremely well for the company. Most memorable for me as a brewer, was the manner in which huge monetary savings/profit gains were made by successfully implementing variable cost reduction initiatives. For instance, a brewing ingredient switch was made to a more readily available local alternative which was many times cheaper, resulting in phenomenal savings and progressively increasing profit earnings even though the price of beer produced was not raised. This practice was routinely applied across the brewing and packaging processes in line with a well thought out plan.