Skybus from melbourne southern cross station to tullamarine only takes about 30 minute each way. Ticket can be purchased from machine and cost 19 aud.
Timetable is mot shown, because the bus comes every :10 minute.
So, 10 00, 10 10, 10 20, and so on. It is very easy to predict, the bus come timely and service is good. Would recommend this over taxi, actually.