Motocenter AZ has the BrakeTec (who, somehow, acquired the assets/IP of AJP) rebuild kits for the AJP master cylinder. My MC is 20 years old w/o a rebuild, but i have a kit just in case. Much cheaper alternative FWIW.
You need to pay attention to and match the fluid type unless you want to put the corresponding seals into the slave cylinder too. Magura and Brembo have other options.
Thank you for the replies. I purchased a rebuild kit off E-bay awhile back and it did not function. I believe it was mislabeled for the fluid I required. The seals failed in a short amount of time. Fortunately I bought a used assembly and it has been working pretty well. Was hoping to find a newer more readily available assembly. The OEM doesn't appear to protect very well for mud and debris.