You should really try not to worry about the price of the trip any more, it will just spoil the enjoyment!!! It is already paid for and decided. I feel the same way about my upcoming honeymoon trip (Backstage Magic)....I feel like maybe we should be a little more frugal b/c of the economy. But now I have decided to focus on the trip itself, how wonderful and fun and special it will be, and I have realized that in 10 years, or 50 years, I will remember the trip and what a wonderful time we've (hopefully) had. I don't think that in 10 years I will really care if I saved a couple thousand dollars on my honeymoon trip; the amount of money seems big now but not in the long term perspective
So please try to enjoy the trip, I am sure your husband wants you to have a great once in a lifetime experience, and would be disappointed if you couldn't enjoy it because of worrying about the economy/finances/etc. And just think that you'll remember this trip for the rest of your life, and it will be a perfect way to memorialize your birthday with your son