just to give you a benchmark.. .. . We're going to the grande in St Lucia on December 26th for our 25th anniversary and staying to greet the new year. In a swim-up lagoon room with concierge service. Taking helicopter from airport to the Grande (and back) instead of teh Mister Mouse's Wild Ride in a taxi van. (I'll hire a private driver to take us around the island for a day so I don't miss it.

)
Now keeping in mind that I'm traveling at a horridly expensive time for travel. I have airfare and everything coming in at just over 7,000.
My travel agent is sandals certified and has really done a nice job for us. Look around, get several quotes, and don't worry about the money. You get one shot at this just like I get one shot at a 25th anniversary.
And yes, it is more expensive to go to St Lucia than it is to go to Jamaica or the Bahamas. But I don't think you'll regret it.