Need a transfer from Beijing Airport to my hotel in Badaling area (Crown Plaza Huailai - in july).

From what I could find this should cost about 300 Y.
I don't understand while my hotel and some taxi company I contacted asks 1200 Y.
I would like to arrange this in advance, so that the price is agreed (so no hassle after a tiring flight).
Is this possible? Who can do this for me for a reasonable price?
(After a few days I also need to go back to Beijing.)