According to the Sea World website, at gate tickets are $92. You can buy them online for $10 less. If you decide to go, your best bet would be to use the business center (assuming your hotel has one) and get online to buy the tickets and print them out. They also have a $99 Sea World and Busch Gardens one day at each combo ticket available online that's good through May 25, 2014.
Discovery Cove is by reservation only, because they limit the number of guests in the park each day to provide personal service. You might be able to walk up to the gate that day and get in, but I wouldn't count on it.