Obviously Oslo is an expensive destination. For those of you seeking to keep the cost down, there are fairly cheap rooms available at Cochs pensjonat. A number of us (including myself) are also planning to camp. If you don't have a tent, you can also rent cabins. A decent-looking campsite is located just 9 km and a 30 minute bus-ride from the city centre of Oslo. See http://www.bogstadcamping.no/eng/adkomst.php.