Hi Darren,
It looks like the Bison sheet is no longer in production I'm afraid so it's the DIY route by the looks of it unless you can find someone with them still in stock.
You can use an inkjet printer and any graphics program, just make sure you get white decal paper for inkjets - I get these sheets:
http://cgi.ebay.co.uk/Inkjet-water-slide-d...=item19b4ec7e03
(You'll need white, not clear.)
Layout your decals in strips across the sheet starting at the top and just cut off that strip then you'll be able to reuse the sheet next time.
Once you've printed them and let the ink dry, give them a few coats of clear and let that dry thoroughly before cutting them out, making sure you trim right to the edge to avoid a white border.
Have fun, it's quite rewarding really.