As mentioned on my initial post, my pair were $160 to rebuild which covered new seals, and labour for stripping them and cleaning/repainting them afterwards.
Because they are 4 piston unit the price could be higher than a single/twin piston set. I took them to a local shop (Brakes Plus) and he had them back to me the next day.
Dunno what the parts would be worth, but by the time you buy the seals, paint if need it etc it would add up.
I diddn't need any pistons, and he said they were great inside, even though they looked well-used on the the outside.
Oly