I've got no idea what the airfares are like from the US to NZ but yesterday I booked a 7 day trip to Queenstown for two people for $2300 Australian (about $1800 US). That included return airfares from Melbourne, Australia, 5 day lift passes, car hire and accommodation.
Have a look at the websites for the nearby resorts for any package deals (remember the prices on those will be in NZ dollars):
nzski.co.nz for Coronet Peak and the Remarkables
cardrona.com for Cardrona
treblecone.com for Treble Cone
I don't know if you can fly directly into Queenstown from the states but the cheapest way to get there is probably to fly to Christchurch, hire a car and drive to Queenstown. It's about a 6 1/2 - 7 hr drive.