So, ballpark figures are from electrical, plumbing, flooring, drywall, and ventilation. 

Your biggest costs will probably be connecting to the sewer and getting water/electricity into the garage.

When were the Electrical, Plumbing, and Heating last updated3.

It was down to studs when I bought it and I did almost everything except for plumbing and electrical myself.

but also, keep in mind that as much as SF would appeal to buyers, there's really been an uptick in trying to force it down sellers' throats. it's not for everyone. whether we agree with his logic or not, if he doesn't want to SF, he doesn't want to SF. it's a good tool to have in your toolkit, but don't waste energy trying to force it.

Public electricity or solar panels?

It’s sounds like you have limited capital at $10,000 but may have the time/energy to put a deal together? 

Some of my best contractors are ones who made mistakes early, but showed a desire to grow and energy to work hard, and therefore our businesses grew together.

Your time and energy are your most valuable assets. 

Make sure it's by an electrical  Outlet.( That could  cost a little)The Engineer cost is still  going to more and  his report will suggest all that I stated plus much  much  more Good luck