The CHEAPEST way is to get an all day zone 1&2 Myki ticket on the the 901 Smart bus from the Airport, get off at Broadmeadows station, catch the train to Southern Cross, then V line train to Woodend.
The BEST way is the Skybus, to Southern Cross, then V line train.
Skybus into the city and a bus to Woodend from Southern Cross.
Can't you get someone to pick you up? Woodend is a small town. There aint much there in the way of tourism.
Does that take you from the airport? There's a bus that runs between the airport and Southern Cross station (Skybus I think?) and from there you can take a V-line train straight to Woodend. I don't know prices, but hopefully this'll help :)