I'm not really sure what the real estate contract states here in NC, but in AZ the buyer has a specified amount of time known as the inspection period to which they are supposed to hire a home inspector to look over the property.

This is a very rough estimate and are handyman prices not GC prices.Central Air $3500 for new A/C unit.Ductwork estimate $800.Paint exterior $1500-1800Landscaping, removing trees,  depends on house but $500-1000Removing tool shed or items from back yard $500Roof estimate about $200 per square  (100SF) of roof. 1200 SF house roof around $7k-$9KSeptic System/ Drain Field $5-$7K or moreWindows can be very expensive and require permits in Fl. about $500-$1000!

The fact that you can do work yourself and this is the course you want to take means you have a lot of advantages of those of us that hire out absolutely everything. 

The yard maintenance would otherwise be $80/mo to hire it out. 

I would hire a real estate lawyer tomorrow and start the process of having them evicted.

If it is really bad there are companies you can hire to help.

We hired Orkin, for 1 year.. every 2 months, they "sprayed" and we confirmed with the tenant that he could let them in the house... so we thought everything was settled and taken care of.. he did mention ants another time, but nothing more .. 

@kevinpolite It's in okay condition, it's centralized heating and air, there are tenants currently in it; Just needs mainly a cosmetic lift.

I have never "steered" any client away from an FSBO, however I do have an obligation to inform my client that, as per the buyer-broker agreements in my state, if they have hired me to help them purchase a home, and the home pays less than the rate that was agreed to on the buyer broker agreement, the BUYERS are on the hook to pay the real estate commission. 

The only thing is your content must be properly defined to make a person want to hire you.