I recently did an experiment in which I went to the Goodwill Outlet (pay by the pound) every day for 30 days.
At the end of those first 30 days I had a profit of $1,300.78. This was actual profit after all expenses. 9 weeks later, after more items sold, the profit from stuff found during those 30 days was up to $2,458.17. I usually stay away from clothes, but I do like shoes. I like media items the most, which are video games, audiobooks (mostly self-help), and niche CD/DVD courses.