Can anyone tell me if there are any budget airlines flying between Auckland and Christchuch?

We are visiting on a reccie soon and are staying in Auckland however I would like to fly to Christchurch for a couple of days so that we can drive to Lake Tekapo and visit the church that we got married in 4 years ago.

I have looked on the Air NZ website and although their prices don't look bad If I can get them cheaper even better!

Thanks

Kerry x