Copy data from excel

I am wanting to write a script that will open several excel files and copy data from one cell then enter the data into another excel file. 
 
Basically I have several excel files coming in everyday.  Each excel file has a total on it.  I want to 'collect' these totals and input them into another excel file, or possibly even just tally a total to a text document. 
 
I need to do this in order to reconcile invoices over a month's period.
 
The caveat is that most of the excel sheets contain the 'total' in the same cell on very sheet.  However, another client has them in different cells every time, although it will always be the bottom, right-most cell (if that makes sense).
 
Any and all help is greatly appreciated.
 
Thanks,