The ultimate calculator side hustle

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Ten years ago, Justin Supak, 39, stumbled across something silly on eBay: used graphing calculators for sale. He happened to own two calculators from his college days at Texas A&M and had no idea they might be worth something. “I just tested it to see if you could actually sell them,” Supak says. “I listed the two on eBay and they sold. So I was like, ‘OK let’s see if we can get more.’”  

Supak has now run for 10 years as a side business to his work as an IT service desk analyst. His platform provides an easy way for people to sell calculators, which he then sells at a profit.