Company is Parking Port and the usual charge is $104. Valid to: 28 Nov 2014 If you want extra days, then you just pay the difference at the counter. You can use this voucher for less than 14 days but obviously 14 days provides the best value.
Comparing to others:
Melbourne Airport: $115- 15 day special
Andrews Parking: $119
Ace Parking: $132 1 day free may take a tiny bit off
Busy Beaver: $110
A1 Parking: $113
If you don't mind leaving your car in the street: ~$7
Of course, I probably don't need to mention that there is a Skybus ($30RT) from Southern Cross, the 901 bus/train to Broadmeadows (a few bucks), and Uber which provide alternative ways to get to and from the airport.
601 bought at time of posting. Don't forget ~4% cashback with Cashrewards/Starthere.
Ah yes, Skybus… the service that's pushed by the Myki trip planner but you can't actually pay the fare with a Myki card. Wow, nice one Melbourne! A great introduction for visitors (not).
Other than that this deal seems OK and the comparison is handy, cheers ;)