I’m sure the U.S. could sell a few mothballed LA Class attack sub at a reasonable price.
Afterall our navy is shrinking in size and the democrats won’t provide the funding to run them.
The sale of N-submarines is banned under some international convention, though there is no restriction on leasing.
But on a practical level, cost and logistical challenges would probably stand in the way of any such deal with Australia. The current Australian Collins class subs require a crew of less than 50 while an average L.A class boat has complement of about 100. And the RAN is already facing a shortage of submarine officers.