commerical products are pressed and not burned so even if you coul dget a hold of the media you'd have no way of putting any data on it.
if you live in the US, the Epson R series printers are your only option for printing on discs (and you must buy printable discs, not regular blank media)
if you live outside the US there are also canon models available. these aren't availlable in the US due to patent disputes. (the model itself is available, but not with the printing feature)
and for the love of god do NOT use stick-on labels. those are certain death for dvds.