That being said, it's possible to get permits in retrospect, but you often have to do some demo and rebuilding based on how thorough your inspector wants to be. 

I believe different locations and demo's have different marketing approaches.

That way we can keep the bathroom and not demo the walls, unpermitted building interior work. 

@Yang Zhuang4 family renovated can probably go between 1 to 1.5 million (depends of  the area, number of bedrooms per unit, age, etc.) in Bergen Lafayette.

Self Storage Project WorksheetDrive up StorageNotes:Land$200,0004 acres at $50,000/acreSurvey$7,000Site, elevation and building layoutFence$30,000Black chainlinkGate system$25,000Automated rolling 20ftEngineer$30,000Dirt work$15,000Building demo$Electrical- site$7,000Electric poles$Security$10,000Storm drains$150,000Water$5,000Water line$30,000Fire Hydrant$3,000Sewer$7,000Sewer Line$7,000Buildings$1,180,800Phase 1 2 acresOffice$25,000Office setup$5,000FootingsRoadsGravelAsphaltConcrete roads$676,1336 inch Cubic yards, framed, poured, sawn,Retention Pond$5,000Landscaping$5,000Road Sign$15,000For highway 55mph billboard signTotal$2,437,933Self Storage Purchase:Same situation as above, but we are purchasing a pre-existing Storage location.

In two cases the property was listed a few months later for less than what they had paid for it after a demo had gone off the rails.  

I have a demo scheduled with them for next week so we will see how that one is. 

You have to pull out everything, demo the drywall, hire a drywall crew to hang new drywall, then put everything back and paint.  

Large demos I've rented haul away dumpsters for ~$500, otherwise the self haul site near me charges ~$40 per drop off

They have a 30 day free trial and you can set up a live online demo with one of their Reps also.