Also I think what is messing up the automatic valuation to such a low number is perhaps the comps being used are not waterfront. Also there is not a way for an automatic valuation system to know about the over $100k in upgrades/updates you've made to the property.
If you would like the highest level of opinion to get a current market value for your property before listing it for sale, you may want to hire licensed Florida Appraiser. That way you will not list it too low and leave money on the table nor waste your time by listing too high and never sell until you through a series of price reductions.
Let me know if we can help.
All the best,
Alma Rose Kee, PA
Future Home Realty
Trulia pulls information from the public records and other various sources. No one at Trulia verifies the information so there is a lot of incorrect information. I personally would not worry about what Truila says. If you would like to know the market value of your property I would suggest contacting a local Realtor.