My 10-year-old son brought home a book from our park’s free library box. It was a biology textbook – teachers edition. He said it looked interesting and hey, it was free (having no idea you could sell it). I scanned it in my Amazon seller app and realized it was worth around $150. He was so excited. We listed it for sale for $130 and it sold! Going to tell him, he just made $130!
It’s one of the oldest and most proven ways to make money – buy low, sell high. The buy low part comes from searching garage sales, estate sales, and even thrift stores to find items that are in good condition (“gently used”) but selling well below what they would if they were brand-new. In this way, you might be able to acquire an item for $5, and later sell it for $50.