Mother Goose,
I think you are referring to 'Littlies'. They also fit out my way (Berwick/Narre Warren) and do the same things as you said. If you've bought it from Babyco, Snugglebug and a few others they will fit it for half price. He told us $25.000, normally $50.00. He goes to each store on a particular day and you just ring the store and book in.
He said that they are not the cheapest going around and strongly suggested getting them fitted by a pro. I am going to check out the Ambulance Service in Vic like Jacqui suggested.