Create 128 Barcodes within Excel
You could try the Free Barcode Font downloaded from here: http://www.barcodelink.net/barcode-font.php and install it into /Library/Fonts.

To use it just choose the font** in any Application you want - including Excel.

The barcode will properly need to be in a larger font size then the rest of the cells - but you can try it out your self - maybe it is "good enough" for you.

It is not the best solution - but it is free. Alternatively, you can buy a solution - a search on e.g. Google will give you some hits.

** It is showing a barcode icon, and not the name, but it is located in the C's because the name of the font is code128.ttf