Central HVAC add ROI

[Rick Nightingale]

I am purchasing a REO for a flip (or possibly to hold and rent for a while). It currently has electric baseboard heat and the previous owners used window AC units. It is a slab on grade house so adding central forced air would require a package unit and ducting through the attic to the tune of about $13,000. Is this an investment that is worth it or is there just no ROI for upgrading? I know it might make it sell faster but I don't know if would bring enough more to justify the cost. Thanks, first time poster, first investment property. .

I should add that I am a remodeling contractor and will do all of the work myself other than this.