http://www.horizonsunlimited.com/hubb/south-and-central-america-mexico/crossing-darian-gap-only-230-a-42769#post252653
Trip report on crossing the Darien Gap for $230, took ages, 5 separate boats, lots of wetness, sounds like an adventure!
http://www.hostelwunderbar.com/
Hostel in Panama recommended on the HUBB (horizons unlimited) as a place to start a crossing of the Darien Gap in Panama.