Purchasing Unpermitted additions

[Andrew R. Lucas]

Need some advice...

1200 sq ft original home in up and coming neighborhood.  Homeowner added 1800 sq ft out the rear and in the attic of original home.  All additions are still in "roughed in" state, i.e studs, electrical runs, and plumbing runs, but no outlets or valves.  Sub-floor down and no Sheetrock.   

NO permits or inspections were ever done.  Should I run, or work it out?  Has anyone ever successfully completed a project where you need retroactive permits?  

ARV = $230k

Purchase = $65k

Repair = $60k - $100k depending on if it has to be reconstructed to meet code.