Property "values" done by Real Estate type Websites are rarely accurate on "average homes in the area". Much less even, on unique or specialty properties like yours. I would not be too concerned about the valuation done by impersonal software with regional data that will rarely be accurate or updated...
The main concern is finding someone who will value your property in the same way that you do. If that someone also needs financing, then you will need their mortgage Co. to see it the same way that you do. That will happen only "IF" it does appraise @ that same #. The appraisel done by the actual lender is where the rubber meets the road.
Good Luck! - Fri Jan 13, 2012