Looking at a property with 125ft of canal access on the backside with enough dock space for a 30ft boat.  Located in zip code 32257 and the canal has direct access to the St. Johns River in Jacksonville, FL.  Think the property is overpriced, but how much value do you think the canal access would add to the property?  It's a bit unique in not many homes in the area of this feature and even fewer of them have sold in the past 2-3 years that I'm aware of.  

Speaking in more general terms, when you have properties with unique characteristics, or not many comparable that are relative, what steps do you take to value the property?  Seems with properties like this it's 50% science 50% art and just know the area very well by seeing lots of property.

A canal can be a blessing or a curse. You are more likely to turnoff families who would be worried about small children. There is some added expenses that can come up with the retaining wall etc. I would look at the homes that sold with canals and their comparable sales history of properties without. So if a 1500 sqft 3/2 goes for 300k on the canal but 265k without you've got your answer. Try to analyze a few of them to get a feel for it. Come up with an average value add for the canal.