For village stay from K50 to K100 - K200 to be on the safe side. Its not a well developed industry at this stage. For trecking, a budget of around K200 per day or maybe more. Like i said, you would need to get intouch with tour operators there. visit the http://www.bougainvilletourism.org.pg/ website and see tour operators or get intouch with http://www.bougtours.com/ and organise something with Zhon.