This is different from the UPC code, which is the actual bar code. Now, I've got the the ISBN, but I needed the UPC code. These can cost you from $10 - $30 per barcode (crazy, ain't it, paying for the code of a number you already own -- the ISBN should just include the danged thing).
Fortunately, there are free barcode generators out there, and here's one I use (and recommend):
Since this is a free service, be a sport and donate a couple of bucks if you use this service.