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 addition, visualise it having dynamic query/report drop menu interfaces, and a variety of custom buttons: for navigation(within and between worksheets), printing, data export (as PDF documents or spreadsheet files), saving, auto_data filtering, auto_charts plotting, auto_backup of files, user login authentication (for documents with sensitive or confidential content) etc.
It's not enough to have a professional with the technical skills to solve your problem. s/he also needs to have the right attitude and background/experience _ else the relationship will not work. This is where an Excel VB resource is more likely to add value to you. Most Excel VB Developers have backgrounds in management, accounting, engineering and other fields, which further equips them to be useful to you in "thinking up" better ways to apply your spreadsheet automation to get the most value for your business. You therefore need to choose the right developer, with the appropriate background to match your needs.
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).