Be sure to no only account for the cost of the cash for keys but your additional holding costs while you have to wait to get them out.

I also suggest that the tenant install a camera that stores videos of the driveway, then when tenant has proof, you can send notice to owner next door that he is to eliminate hazards he is creating, or you will sue for damages, especially if it costs you tenants, as they can’t afford and shouldn’t have to deal with repeated damage.

Was the owner doing his own repairs and hiding the costs?  

I will say REPS is one of the areas of the tax code where it is very costly to get wrong.

In Milwaukee, I'd need 2 exits from the attic and 50% of the space has to have at least a 7 foot height on ceilings.Two things you want to check: both requirements are correct, but on top of that the city is getting reluctant permitting 3rd units: 50% more occupants mean 50% more water and sewer and 50% more traffic and parking.The other issue is that the cost of finishing a thrid floor with proper insulation/ventilation will run about $50-60/sf and only makes sense if you can get strong rents. 

What's the cost?

Get caught with your pants down on paper first, it costs less. 

If you are in the actual SubTo community, there is no way they haven't been spam calling you and grouping you so you should have access to that inside of the Facebook page or paid groups.But, seconding @John Clark, if you are new as an investor, choosing SubTo is going to cost you a lot and get you a little.

You could even team up with other investors to split the costs. 

The below is the closing costs breakdown the lender has provided.