In each of the six ski areas in the region (Hohshvartsek, Gёtshen, Jenner, Obersalzberg Rossfeld and Zinc / Rottenlift) you can buy a ski pass. But it's more profitable to take a single skipass of Berchtesgadener Land for all six ares of the region for a period of 3 or 6 days, which includes even the bus, plying between lifts Oberau / Rossfeld, and 4 hours visiting Watzmann Terme (without sauna).
Ski pass for an adult for 3 days in 2013 costes 93 euros, for 6 days 153 euros, for children up to 13 years (inclusive): 46 and 90 euros respectively. There are discounts for young people up to 18 years. Attention! The information about the prices and terms is valid for 2013. Please specify the prices upon arrival!
And do not forget to take allways your guest card (Gaestekarte), which you will be given you on arrival at the guest house. This card provide different discounts at the regions. You can not buy even the skipass for 3 or 6 days without it.
Information about ski pass can be found here:
http://www.berchtesgadener-land.com/natur/winter/skigebiete-berchtesgaden-koenigssee/skipass-preise