We also loved Discovery Cove... of course, it is not the only game in town, as they say. Many of the Mexican resorts and many cruise lines offer "swim with dolphins" activities, so if you aren't planning on being in Orlando for this event, there are other options. (I believe it is illegal to swim with wild dolphins in the US.)
That said, let me quickly give you an idea about DC. The price, up front, does look pretty steep, but there are a few things to consider. First of all, if you and DH don't want to be in with the dolphins, that drops your price... plus you can still be nearby and watch and photograph.
Second... EVERYTHING is included for the day. Show up with your reservation, swimsuit, sunglasses, and towels, and you are good for the day. They included sunscreen (a special kind that doesn't pollute the water for the fish and dolphins), wet suits and/or vests, life jackets (if needed), beach toys, swim mask and snorkel (you get to keep the snorkel!), and FOOD!! There are snack bars everywhere and lunch is included! Plus the showers had body wash and shampoo!
Plus you get your choice of a 7 day pass to either SeaWorld or Busch Gardens Tampa along with your DC admission!!
I, personally, think that DC is a pretty good deal... especially if you can take advantage of a few of the SW or BG admission days. Sadly, we could only work one into our schedule when we went.
If you have any questions, let me know...................P