Rather than spending all the money to furnish the unit for it not to be successful... and have to sell or put all the furniture in storage and create another expense. 

You can also invest in self-storage units.

I love self storage.

First decide the area(s) of interest to you as an investor - both geographically and the type of investment (SFR, small / large multi, storage, etc).

In my case, I have residential rentals in one LLC, commercial properties in another, self storage in a third, and my real estate company operates in a fourth.

That's where bad experience/nightmare come in.Lastly, to answer your question, to build a basically designed, square/rectangular house without crazy jigsaw puzzled cuts on roof, the following price is a good competitive construction only price for what you need to do:Around $165 per sq ft on conditioned space (for an average 1200 to 1800 sq ft house, 8-9ft high ceiling, everything is investor grade finishes), $90-100 per sq ft for garages/unconditioned storage, $60 per sq ft for porches/opened spaces.  

Things like office, self storage, retail, etc.   

ADU, parking, storage, laundry).

The structure and roof is good with some issues I want fixed:-covert fuse box to 200amp cb panel-storage shed/garage water damageI’m seeking advice on how to make an offer with either the seller repairing these items (another investor I’m not sure I trust to do it properly) or asking for funds at closing (escrow). 

Our Self Storage developments, the same thing.