Magnetic Island near Townsville is a pretty cheap option, although as a local kiter I don't think the wind is consistent enough to wager $5K kiting holiday on it. It would be great if you scored a week of 20-25knots however!
info here:
http://www.tevenei.com/tvm/nellybay_kite_map.htmYou might want to think about Port Douglas with a little camping weekend out to Lizard?
www.tevenei.com/tvm/lizard_kite_spots.htmTalk to Marvin from In the Loop Townsville about Lizard trips, and also his recent trip to PNG - it went off apparently, heaps of 25-30kn winds, blue lagoons, waves, relatively cheap access. They have some more boat trips in the pipeline for this year and 2010.
www.intheloopkiteboarding.com/Of the South Pacific destinations, New Cal is good but exxy. Vanuatu and Fiji might be better options.