Answered my own question-
Spoke with Qantas and found that as a non-refundable ticket no refund available, which seems imminently logical- so apparently you take your chances when you buy that the ticket might be cheaper in the future. If so, you lose. But... if the ticket price increases in the future, you win!
I was basing my question on UA's policy of issuing refunds for the difference if the price of a purchased ticket decreases.