I've found this exelent working PHP script that makes the barcodes. I've found it at this page
$bc = new Barcode39("123-ABC");
$bc->barcode_text_size = 5;
$bc->barcode_bar_thick = 4;
$bc->barcode_bar_thin = 2;
Would there be a simple way to make this script write multiple barcodes with different values in one page?