I would spend your time and energy being proactive and fixing the tenant screening issue rather than going after the lost rent and repair expenses.

Here’s a quick breakdown based on my experience:Building new construction gives you full control over the design and materials, allowing you to incorporate the latest energy-efficient systems.

Plumbing, Electric, HVAC, Drywall, Gas etc.

I’m defining general light work as plank flooring, painting, minor electrical, etc..For example - is it fair to estimate flooring labor as $3/square foot?

Owner is motivated to sell and says expenses are $2300/month (includes lease rent 1700+600 in electricity/gas water included in rent).

But each technology needs to show why it should and will be adapted, just like wind and solar have, along with ESS (energy storage systems), in the US market. 

Tenant shall properly use, operate and safeguard Premises, including if applicable, and landscaping, furniture, furnishings and appliances, and all mechanical, electrical, gas and plumbing fixtures, and smoke alarms, and keep them and the Premises clean, sanitary and well ventilated.F.

We also had some exposed wires under the house that required some minor electric upgrades to bring to code.

Then go price your labor plumbing electric, roof, finish outs, and landscaping.     

Still you’ll need to fix any plumbing, electrical, door etc type issues which likely are in bad shape.