Interesting off-market rehab. Thoughts?

[Justin H Harstvedt]

The beautiful home came to a halt halfway through construction. Sounds like the county shut down construction due to elevation or possibly FEMA issues. The owner seems to have just moved on emotionally and cut his losses but would like to get as much out of the deal as he can manage. This is way out of my expertise level. I don't even know where to begin to see what it would be worth an investor to pay because I don't know if the structure needs to be demolished or if it can be salvaged. He originally thought it had to be torn down and wanted 450k for just the land but now seems to be under the impression that it can be completed and tells me he thinks he can get 900k for it. The property is in a fantastic location on St. George Island, Florida. I'm at a loss on how to proceed.