Garages are often cheaper to convert to ADUs than ground up construction, but not cheap enough to obtain a profit worth the effort.  

Columbus has some strong dynamics…cheap prices, 3 F500 companies, military, hospital, kayaking enthusiasts, Kia car plant.It has as many bad parts as good, so do your research, but I do believe if it is just about the investment, there’s some money to be made there

If you are convinced this is the guru you want to follow, pick up a cheap resale on amazon or ebay...read and study it cover to cover. 

  $560 is pretty cheap. 

I agree with the need of a furnace.Most mountain cabins have hot tubs.Emergency generators aren't cheap, but great to have during a sustained power outage.I've thought a battery backup system might be a good compromise.

Cheap house with a decent profit How did you find this deal and how did you negotiate it?

Those ain’t cheap, and one good catch by the inspector saves you all the money you spend on all the inspections.There’s an old saying: “Life is hard.

cheap houses are generally the most expensive

IE. if you buy cheap area you will likely have tenants who are not able to pay top dollar etc. 

Properties are very cheap, real estate taxes are insanely low.