What is the best rate for Phi Phi day tour in June?

I%26#39;m planning to visit Phuket in June next year... one if the activities in my itinerary is day trip to Phi Phi and i have a few questions as below:-

1) I was told that it%26#39;s cheaper to book the day tour from travel agents available in Phuket compared to those online. But i came across this website (www.tour-phuket.com/show_package.php?id_loc=3) which offers only 850 BHT for the Phi Phi day tour and i was so tempted. May i know what is the cheapest rate i can get from local travel agents during low season (June)?

2) I read from reviews saying that Phi Phi island is always packed with visitors and the environment is not as nice as it used to be. Is this place still worth visiting?

Thanks.