Australia's interim SSN fleet would be limited by cost and capacity

Could Australia receive as many as five Virginia-class submarines before building its own AUKUS SSN?

Probably not; three was a more plausible maximum because five would be exceptionally expensive and difficult to procure.

Five Virginia-class submarines appeared too expensive and difficult for Australia to procure as an interim force. Three boats were offered as a more plausible ceiling, with the caveat that the official announcement had not yet been made. Affordability, available boats, and the transition to an Australian-built SSN were the central constraints. Any alliance plan still had to pass through national budgets and industrial capacity.