Bucket trucks (sometimes called boom trucks) can be purchased at both online or in-person auctions. Many familiar online sites, like eBay and Craiglist, contain listings for bucket trucks. There are also heavy equipment auction sites, such as CommercialTruckTrader.com designed for this purpose.
Due to the nature of commercial equipment, it is preferable to find a nearby auction where the bucket truck can be personally inspected before purchase. Generally, auctions are held on a specific date and are open to the public. Many companies now post the equipment online before the auction is held, so buyers know ahead of time what will be available.