"off the shelf" for military hardware is to buy a current mature production model configured per a standard spec instead of some hybrid models where the customer wants to customise it. e.g. fitting completely different systems etc.
RAAF successful purchases as stated are the C-17/F-18F/CH-47D/F [to come] which were purchased from the US production run with US standard options.
I'm amazed that politicians and defence neddies talk about standardisation then don't do it!