It varies every year. Last year it was quite reasonable (2 adults 2 kids 21 nights):
14 nights AKL, Virgin flights, full size car (Free FV upgrade) -£2895
7 nights Polynesian Concierge £1500
Upgrade to PE homebound - £500
Already had APs from last trip, so Universal 5 day 2 park pass for all of us £100
Sea World tickets - £100
Total - £5095 plus we spent probably £2-3K when we were there.
This year - more of us going! 3 adults, 2 kids, 1 infant, 23 nights Xmas & NY 06/07:
Virgin flights - £2100
PE upgrade return flight £700
5 bed / 5 bath Villa Windsor Hills - £1900 (inc pool heat)
Van hire - £520
Tickets - 1 AP - £230
2x adult 21 day WDW passes - £340 2x kids 21 WDW £300
Sea World / Busch Gardens combo - ££225
Total before spends : £6315
Spending Money - Probaby £3.5K