I had a look at these on ebay, a bit rich for me considering I would still need to buy extra cutters, but hey, I am sure plenty of us would love to have one of these!
http://www.ebay.com/itm/Valve-Seat-F...622659&vxp=mtr
http://www.ebay.com/itm/Valve-Seat-F...622659&vxp=mtr