Cocos is an amazing place to visit and kite. It's one of those rare places where the trade wind blows non-stop 24/7.
The wind can be quite strong as well, last season I kited a lot of days on 7m and 9m kites and the 12m got the least amount of use (I'm 82kg). The 17m I also brought remained completely untouched! That being said, last seasons winds were unusually strong and you can always get a week or two of 12-15 knots so you have to be prepared for this...
For me the major downside is the wind was always varying about 5 knots in strength on any given day, sometimes more especially as it gets stronger (we had many days of 20 knots gusting 30 knots). If you are used the steady sea breezes in WA you'll find the wind in Cocos to be quite different...Most of the time it felt exactly like kiting at Point Walter in morning Easterlies.
You also can't kite on low tides as the water is simply too shallow and a lot of times at lower than mid-tide I was holding back from boosting and doing tricks as it gets very dangerous with shallow water and the reef/coral everywhere, so high tides were a must for me. The reef is sharp so if you intend to stand after you crash you must wear booties as a good reef cut can quickly end your expensive trip. I didn't wear booties but I never stood up and always body dragged for my board after a crash even if I could stand up easily.
Visiting the islands is awesome and you can even kite across the lagoon (best if you can find boat support), then snorkel as well in the same day:
The cheapest form of accommodation will cost you about $150 per night. Food is 2x as expensive as in Perth. Liquor is very cheap (duty free) but beer is about the same price as it cost much more to freight it than liquor.
A moped or even a bicycle (if you feel like exercising a bit) will get you anywhere on the island in minutes. Car rentals are very expensive (about $100 per day I think).
As others are saying, if you are already a competent kiter, organizing your own trip is the best and cheapest way to go. You will meet heaps of other kiters doing the same trip as you.
EDIT: I forgot to mention, bring spare parts! Spare lines, bars, valves, tear aid. etc. I came across many kiters who brought older gear and had to get it fixed and sometimes it can't be fixed due to lack of parts!
Christian