One way I made extra money was by playing online poker. I wasn’t the best poker player, but I was decent enough to profit a few hundred dollars a month.
Most of my dollar store and garage sale purchases were smaller wins. For example, videos purchased for $1 would often resell for $8 to $10 on eBay.
At garage sales, I usually did well with video games, board games, VHS/DVDs, athletic equipment, and sports memorabilia. For example, I once came across a copy of a rare Super Nintendo game called Mega Man X3.
Take advantage of your smartphone when looking for items to resell. As I browse garage sales, I usually have the eBay app up with the proper filters (e.g., completed or sold items).
Negotiating a $20 item down to $10 can make a big difference. People also seem to be more willing to lower the price if you are purchasing multiple items.