|I'm not an expert on OpenOffice but a Google search on password protected Excel files seems to indicate that OpenOffice 3.2 and later can open them.|
If I were in your position, I would certainly try it since it's free.
If it is your understanding "that there may be a way" to open them without purchasing Excel, why don't you share what that "understanding" is?
Better yet, why don't you try whatever it is that you "understand" can open them?
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.