You can pay for a font if you want, or get a free one.
Probably some of the easiest fonts for someone to code, because it would
be right from the specifications so why one would want to pay for or believe
that they have to pay is beyond me, especially if you only want one type of
barcode. Some barcodes may require a macro to complete a check digit.
http://www.mvps.org/dmcritchie/excel/mailmerg.htm
It would also seem likely that a barcode reader would come with software.