If I don't have $30K to $50K to invest in an HVAC for the home, the next best is a relatively efficient Window unit that costs low hundreds and will help me stay alive in the heat. However enticing the price of a single duct portable unit is, do not buy it. It's a complete waste. If you go portable, go with the dual ducted one --but it's still not as good as a Window unit (which I would hope is obviously less efficient than a properly specced HVAC unit.