Try a friendly brake specialist. Most can't be bothered, however there are still some that seem to be prepared to help. I've got a local guy who is pretty helpful. We also have a local guy who re-sleeves cylinders and calipers with imperial sized stainless. Last time I checked it was $200.00 Au for the front master cylinder re- sleeve and new brass piston, and once done replacement cups were $10.00 Au. He guarantees and tests all work, and will ship overseas. I've gotten rear master cylinder boots off him for $4.00 Au.
Regards Martin.