You can call Jason at Alfissimo. He supplied me with OEM rotors and Porterfield pads (or he could have supplied me with OEM pads as well).
www.alfissimo.com.
You can also go online to Rock Auto and get aftermarket rotors and pads, much cheaper and some people have used them with no problem but buy the high end versions and carbon-ceramic pads.
I had my local Indy tire shop install, they do lots of high end cars, or a good Indy shop as well there is nothing special to the job. All in about 1/2 the price of the local Alfa dealer. The dealers love doing brakes, it is fast/easy so the make a lot of money there.