Users sign up, log in and then control finder bots. These finder bots are positioned in front of bins that contain junk, scraps or possibly bulk auction purchases. There are multiple payment plans for using the bots.
One payment plan may involve purchasing a box and filling it up, another may be "finding" with other users (cheaper) and protecting items that a user wants. In the end, a user gets shipped a box of stuff that they scavenged.
User pays for time to use the bot and searches through pile of stuff with other users. After a certain amount of time, the stuff that is protected by the user, the user can keep.
Paid hunters sort through things alone. They buy time, a box or via some purchase model that allows their findings to easily be packaged and delivered to them after they have completed a find.