Imagine shipping a few old calipers from Australia in order to get that measly core charge back. Not economically viable. I'll just rebuild my old ones myself when the various kits/pistons pop up on ebay or wherever at decent prices, even then I suspect the cost will probably be pretty close or even more than getting rebuilds shipped over from anywhere. Locally, nothing is cheap. Honestly it will most likely take me a year or two to gather everything and get it done but they won't get thrown away at least.