Look on attractiontix.com. The offer as mentioned above still stands. As it looks from the description, you can purchase 2 days for the price of 1 for £15 per adult, if you use the second ticket before the end of June 2009. When booking, you have to enter the first date you are planning to visit, and upon arrival, you can pick up the tickets for that day, and consequently the tickets for the following day before June. It works out effectivly £7.50 per day - the cheapest I've ever seen. .The first ticket must be used on a weekend in march, either the 28th february, 1st, or the 7th and 8th march. Unfortunately you have to go to the first day (I.e.: you cannot just go for the second day), to collect the tickets for the second day as well.