Unfortunately, I still can not be of much help. I need specifics regarding the cabin, the septic, etc. There are 3 "cabins" listed in the MLS in Willow on 4-6 acres. I'm sure there are many more listed on Craig's list. The range in price from $18,500 to $130,000.
Please contact me, or another Realtor in the area, via e-mail, Beth@BethsValleyViews.com, and that way you can get more specific about your property.