I've done it twice, excellent dive. Bring money to buy the dvd of your dive afterward - it's quite nice. I call it luxury diving.. you get into waist deep warm water and they gear you up. Totally cushy, more big critters than I've ever seen on a single dive in the ocean. You're only allowed to bring your own mask. The rest of the gear they must provide in order to keep out contaminants.
You get your own locker, a naui bag, stickers etc. They have hot showers with good privacy. Easy access. A "drying machine" which will spin most of the water out of towels. It's all good. Also you get into epcot for free after the dive. The earlier in the day you dive, the more time you get to spend walking around epcot for "free" (the cost of your dive). It's not like you're sneaking in or anything, the exit from the dive is in the middle of the park.
If you want to do it on the cheap then get a small group together. Call them for details but you can do "private group" dives where you get the whole aquarium. I think it was like $1,100 and you could bring up to 11.. can't remember exactly but I do remember noting that if each diver split it evenly it was $110 instead of the $175 that most dive shops in FL charge for this dive. The drawback is these are the last groups of the day to dive so there is less time in epcot after your dive.
Of course for that you need 12 divers or whatever it is.