how can I get from hangzhou to Ulaanbaator Mongolia..

hey, I'd like to know the best and cheapest way to get ulaanbaator from hangzhou.. may be first, I should go to bejing and then take a plane or train to ulaanbaator. what would be the cost of plane?? or is there any express coach to get beijing here in hangzhou.. plse let me know as soon as possible. thank u.. I'm planning to depart hangzhou 30th of June..,