As I am sure many users of the forum can testify , I have written much about the disc brake conversion. As far as I am aware all of the few suppliers are expensive , I know as I bought one which is exactly why I started my own investigation over a year ago . Facing the challenge I put my time and money into the project . Net result is that the conversion for cars with 13" wheels is the way , way , way most economic system. If you are thinking of buying one of the current "off the peg" systems I suggest you ask to see the disc brake caliper carriers , discs and pads alongside the original Fiat parts. If it is a system for 12" wheels in my experience they are all going to be modified "specials" , structuraly weakened and replacement parts will have to be made to order ie if your pads wear out you are screwed. Non of the current suppliers of the full system , as far as I am aware , offer a spares back up system for the stuff they sell so you can spend £500 for a throw away item when it is worn.