The best price found from United States to Melbourne is on August 31st, 2016, travelling with Qantas. See more options, compare prices and book: search flights.
Two airports serve Melbourne: Tullamarine and Avalon (located en route to Geelong). From Tullamarine, domestic and international flights at offered by Qantas, Jetstar, Virgin Australia and Tiger Air. Presently only Jetstar serves Avalon.
There is a left-luggage facility in Terminal 2 at Tullamarine Airport. It costs $15 to store a backpack or suitcase for 24 hours.