What's the fastest, cost effective means to travel from Queenstown to Auckland?

I have to catch a 5:30am flight in Auckland and I'll be coming from Queenstown. An 18-hr road trip is not ideal for my situation since I'm an obvious tourist. Is there a transportation by sail or train? Last resort is via air, any idea how much it would cost, or any suggestion perhaps?

Take a look now at http://grabaseat.co.nz
Quite often they have fares for a dollar! Average fare $39

New cities, fares and seats added every day. It might just work out for you.

For Train you will need to go to Christchurch:

So that option will be:
1. Bus to Christchurch
2. Train to Auckland - Costs NZ$275
Takes 12 hours.

Please note the direct train run only on three days -
TFS (THU, FRI, SAT)

Link for the Trains in NZ:
http://www.railnewzealand.com/

For Ferry - there is no direct service I found.

Hope this helps.
-N

You should find it cheaper to fly If you rail ferry and bus it . you would need to take a couple of days or more The ferry trip Picton to wellington takes 3 hours and costs approx $65 a train trip from Christchurch to Picton is $42 I think that takes about 8 hours then to start you still need to get from Queenstown to Christchurch by bus and train and at the end you need to get from Wellington to Auckland by bus train or fly.

flying would be easiest and only cost $150

Flying would be still cheaper.

An 18 hour road trip - you'll never do it (taking the ferry crossing into account). It's 12 hours to Picton, 3.5 on the ferry and 11 to Auckland. Then, if you're not going to drive, you can double that time using coach transport.
Flying is the ONLY option for you, and seats out of Queenstown to Auckland can be very expensive.
However, book a seat early and you should be able to get a cheap one, as some one says less than $100. Full price by air is around $1 000.
You've got the choice of either Qantas or Air New Zealand.
DriverT