Used 100-pound propane tanks are found at Yakaz's website. Yakaz.com has many listings from people across the country who are selling their used 100-pound propane tanks.
Depending upon the quality, the used 100-pound propane tanks can range from $50.00 USD to $150.00 USD, as of 2015. Several of the used propane tanks for sale are no longer certified, but they can be recertified for use for approximately $35.00 USD. The used, 100-pound propane tanks are being sold by owners all across the country from Georgia to New Hampshire, also as far west as Idaho and all along the east coast.