Complex sentence: A person that buys and collects items (scrap and usable/repairable things) that are considered of little value and resells them at a profit to other individuals and scrap yards.
Split into simpler sentences: A person that buys, trades, or collects items (scrap and usable/repairable things) that are considered of little or no value to their owners. This person then tries to sell or trade these items at a profit to other individuals and scrap yards.