Norway in winter is very, very cold. It is always very, very expensive. It is also very, very beautiful. The warmest you can expect is 5c (41f) and temperatures around -5c (23f) would still be fairly tropical for Oslo in the middle of winter. Personally I'd leave it until summer. Here are the average beer prices in USD: http://www.pintprice.com/region.php?/Norway/USD.htm