I did the aqua tour this past January and loved it. i felt it was well worth the money. You get an Aqua Tour t-shirt, a picture of you right before your swim, and some snacks afterwards.
Besides getting to go backstage, and see all of the wonderful Marine life up close, one of the highlights for me was seeing all of the other guests in the Living Seas pavillion. It was wonderful to be able to wave at a child, and even some grown-ups, and see their face light up.
If it is in the budget, I would definately go for it.