As per Esri's recommendation I began the process of converting my existing VBA customization into VB .Net Express edition. I was surprised to realize that debugging a DLL is not an option in the express edition.
"If you are using the Visual C# Express Edition or Visual Basic Express Edition, you cannot debug DLLs because these versions do not have the option to start an external application for debugging."
Source: http://help.arcgis.com/en/sdk/10.0/a...000001w2000000
Any workaround other than purchasing VS Pro?