I was there 3 weeks ago, and I got a 50rmb discount for the entry fee =)
so what would've been 220 + 90 bus = 310 turned out to be 170 + 90 = 260
I went for two days so it was a good saving of 100 in total for me =)
Also, if you plan to go for more than one day, it's best to speak to your hostel first, they might be able to organise a stay for you with a tibetan house INSIDE the park, but bear in mind there wil be NO heating and NO modern toilets, just very very basic stuff.
My hostel told me about it after my first day, they said I could've stayed over night inside the park for only 90rmb and wont have to pay the entrance fee again~~~~