Sepik River Trip September / October 2011

Hi there - my girlfriend and I are off to PNG on 21st September (flying into Madang) and looking to reach Wewak around 26th September to go and do a trip on the Sepik River. Anyone in the area who'd like to join up to travel let me know. We don't want to arrange an expensive guided tour but if you're interested in teaming up to travel the Sepik let me know.
Cheers