What is the best way from Beijing airport to Babaoshan?

Hello,

I will be flying into Beijing from Urumqi on Jan.3rd. My arrival time is 1230AM (midnight). I want to get to Babaoshan to meet a friend briefly and then get back to the airport at about 6am (I have a 8am flight back to my origin)
Could you please advise me as to what would be the best and cheapest way to complete this task?

Thank you!