I agree they were ideal and it's a shame they aren't available, the adaptor was developed for Sodastream bottles for exactly the purpose of getting portability and that option is still available if anyone local to you stocks Sodastream.
Just ***** me that well my local woollies now wants $14.95 to exchange 330g of CO2 so they are charging dam near $45/Kg, Bunning's was a bit better at only $30/Kg and if it upsets Mark^Bastards delicate constitution; tough that so often retailers here get slaged out even when they are only trying to be helpful, and while offering the same service at about half the price of a national retailer. Guess there's no pleasing some people.
MHB