Ahhh yes! I sent a reply to your message but I'll add a few comments here to share with those who might also be interested.
I flew to St. Thomas on Delta using award travel. I fly a lot for work so the ticket cost me a tax fee of $10. In checking fares to St. Thomas while deciding how best to get there I was able to find a low fare of $390 and a high fare of $1178. The date range you chose is important so it pays to be flexible, as usual, when picking travel dates.
The cottage rents for $1500 / week but there are other units available that are not as expensive. I went with two other couples so the cost was split among the six of us so $250 / person. The cottage comfortably sleeps six with two private bedrooms and one fold out in the living room.
It comes fully equiped with a serviceable kitchen, satelite tv, and even a DSL line so you can keep us posted on tfp about your stay
More information about the island istself including it's history and more information about it can be found here:
http://vinow.com/waterisland/
The place is really a slice of paradise with just enough seclusion to make it seem like you've really stepped off the planet into a world of your own.
Hope this helps!