There's a Public Bus that stops ~50 metres from the Airport West tram terminus that goes on the the Airport.
And as mentioned previously, there is also Skybus which may not be the cheapest, but it's fast, efficient, comfortable and runs like clockwork 24x7. It's also considerably cheaper than a cab if you're travelling with 2 or less people ($24 odd return on skybus vs $45-50 *each way* for a cab).
And there was talk around 10 years ago of getting a train line out there via the Broadmeadows line. All the residents kicked up a fuss and it was knocked on the head. Who knows what the "station access fee" would have been for it here

Skybus uses citylink so it's usually pretty quick too. They will use the express lane in the evenings, avoiding a lot of the jam northbound.
(and I know you know this serfty, just pointing it out to others
