Refinish garage to add space?

[Leland S.]

A house I'm looking at flipping  that is 1350 square feet  but the garage would make a great add-on for 625 square feet extra .  I think to refinish the garage would cost  about 15K .  It would bring down the cost per square foot dramatically  so I think I could add about 30k  to the sale price  easily .  Only problem is now there'd be no garage,   so I was thinking about a carport,  but to me a carport sounds really cheesy  if  the house is new and rehabbed .  Also a contractor said the HVAC unit  is not enough to  provide for that extra area  so I'd have to get a wall mount indoor unit  but that sounds really  tacky to me.  What do you guys think? How do I decide?