[David]

Mini split. I put a 24,000 btu 19 seer heat pump Mitsubishi unit in my 900 sqft garage and it works great of course you could go half that size which would be more efficient at about 26 seer. $2200 with installation hardware. DIY installation is easy if you can get a hold of some gauges since it comes precharged. Plenty cool in Houston summers and warm in Houston winters and it's almost silent.