In addition, an Excel VB developer( who in many cases will tend to be a user turned developer, and is therefore likely to easily see things from your perspective) _ unlike a programmer _ is more likely to be positively disposed to working with you to ensure the application meets your practical needs. S/he will readily understand that the final application is meant to help solve a real problem(s), and will therefore build it to match those expectations.
The 80ᚼ Pareto principle is based on Pareto's theory that 80% of the results one gets in a particular endeavour will be mainly due to 20% of areas to which one has applied efforts. In business this principle has been found to be true. Your data, properly converted into appropriate performance indicators, will show you where your largest margins come from. You can then channel more time and effort in that direction.
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.
Custom spreadsheet solutions which survive long after the developer has "left the scene", are often those which users accept because they discover it _ among other benefits _ makes their work quicker and easier to do. That is why the best person to develop such solutions tend to be one who works in that area, and is therefore familiar with the way the manual system operates. S/he would have an "insider's" perspective of the best way to introduce automation other users will readily adopt _ even as it solves the identified problem(s).