There are a few bargains to be had on the web sites. We used www.attractionticketsdirect.co.uk
You can price the tickets up on site but can't pay for them. You send an e-mail to them requesting the price and they ring you back (you could ask if they can give any further discounts)
We purchased 2 adult and 3 child 5 day park hopper pluses and the same number of tickets of the 5 park flextickets which came to £1354. If you add these up on site they come to more than this as they gave us a further £50 discount for buying both lots.
They are the hard tickets ie. the proper ones and they were sent via recorded delivery within 5 days.
I would do some research as it could work out cheaper buying over there as the exchange rate is really good at the minute. I bought them here to save the hassle once we get there.
Ticketmania.com has always gotten good reviews on these boards - I certainly have had no problem with them. As they are an American firm, obviously it's best to buy from them when the exchange rates are good. Plus postage is free!
Last time we visited SeaWorld they were stamping passes for another free day just as you went it at the entrance. What chance do we stand of this happening again - it will be Easter, same as before? It would be great if it happened again.
Sea World offer the second day free every year at times when the park isn't really busy. They introduce it and withdraw it without too much advance warning and so you may well get the offer again, depending on your trip dates.
I've also found Ticketmania reliable (I've bought WDW hoppers and Universal passes with them), and as Steve says, the free postage makes it worthwhile.