A portable air conditioning unit offers a great way to keep a single room in a house or apartment cool. If you don’t have the room or permission for a full unit, then a portable AC unit is just what you need. How much a portable air conditioning unit costs can depend largely on its BTU rating and how powerful it is. If you have a small room that you want to keep cool, our air conditioner units under £399 should be more than enough to get the job done. Stay cool in your home or apartment with the help of a portable AC unit.