I was told recently by 2 separate places that nobody makes aftermarket air con kits for the micra in Australia any more. So good luck with finding something, not sure what's going to be out there just off hearing that etc..
A full transplant from a wreck might be the go.
As long as you can find the compressor and the fittings for the interior and from there in etc, you can get those custom air con places that will make up any shape lines and you could get a generic condensor and gas canister I think aswell. So maybe you only need a couple of the key parts from a wreck.