No matter how delicate you think your approach may be, some people will take it the wrong way and paint you as predatory.

To me ,without any real information, 2400 is very low to do a full rip out and rehab.

I had some extra appliances and paint etc to clean it up, and currently have it rented out.

These are high crime neighborhoods where someone will rip out $15,000 in damages just to steal $100 worth of copper pipe.  

It has all kinds of new stuff in it and only needs some paint on the inside and then it is ready to go.  

Says need to replace the toilet they would charge a percent of the price of the job@Brian MathewsWhat about recarpeting, paint, fix up a few wall, install a few lighting, repair a few cabinetHow would you classify these?

It would be different if he was a paying tenant who wanted to paint the master bedroom blue instead of the existing white, or who lost his job at a plant and wanted to improve your property for rent. 

also make sure you are covered on lead based paint if the house is older.

Paint ($750)Subtotal $11,50010% contingency ($1,150)Total $12,650Reduction to only adapt existing HVAC system ($2,500)Revised Total $10,150I think the HVAC system is a big determining factor of this decision.

Pictures and perhaps even reno ideas or trends in the neighborhood will help paint the picture for the potential buyer.