Nick_Pyner:
That's fine but I think it's time review the original post which would imply that, not only would you need to know VBA, but also you need to teach Arduino VBA, so it can do the looking. And likely all for no purpose - or no purpose that can't be done with a CSV. I've heard it said that 99% of all the real work ever done in Excel can be done with a CSV file. I'm inclined to believe it.
I reread the original post. I believe the Op wants the Excel up and running continuously and the "Value" shown in the cell to be redisplayed onto a LCD screen. I cannot determine from the post if the Arduino really needs to know the value for any use other than sending to the LCD. So, the procedure would be for VBA to send to Arduino... over serial through the USB port is likely the most viable, although two-way can be established over USB with the right descriptors... perhaps to a Leonardo.
If we could coax Excel into producing a single ASCII file for the Arduino, we would still need to manage the opening of the file and the access to the file data contents. This just seems silly.
Reading a file stream and extracting info is really very, very easy. The character stream coming from reading an SD card is no different, in theory, than the stream coming from a keyboard. I have posted last year a simple example of how to parse and manipulate such a stream (Somewhere in the Project Gallery) but also here:
http://www.hackster.io/rayburne/scientific-calculator
Presumably, the Op's Spreadsheet has a lookup table for UPC being read by the barcode reader. Such tables are likely not appropriate for an Arduino even if we put in additional EEPROM. Then there is probably a price table and tax calculations (assuming a commercial terminal... but it is really not relevant what is being stored and looked-up.) I think the Arduino is just managing the LCD, but the Op probably should confirm that belief.
Ray