I think the problem needs some clarification.
Is this to be a web based application or software and if so what platform?
When you say a database what is the database to hold? is it simply an index of the spreadsheet files and their location or something more?
What do you need to search for and is it the database or the spreadsheets themselves?
If I were you I would move away from excel and use a database only as spreadsheets aren't really designed for managing data for this type of application. If you're stuck with the spreadsheets you can probably work round it.