There is totally no problem with using a used dehumidifier just make sure you check that it is functioning properly before you can spend cash on it—even when it costs too little. Used dehumidifiers for sale can be found in stores near you—I prefer air purification stores that deal with such units. If you have Walmart-like stores in your area, then you can also check with the dehumidifiers section (you should be able to find a unit or two—they are also referred to as second-hand dehumidifiers). If you however need a dehumidifier for rent, you can also find one in stores or even shop online (Read about renting a dehumidifier here).