As goes with most any product, when it comes to selling it, your second concern is how it matches up to the competition. The first issue is "where is the market and how big is the market". In essence, beauty is in the eye of the beholder. I have to imagine that the "market" for buyers searching for pond-property is fairly narrow...witness the number of websites on the internet for pond owners. Now, if you can get the attention of that narrow band of buyers, the value of the generic pricing comp's of similar properties without ponds adds up to fairly little.