Transcript for Cashing in on the Mother Lode of Lost and Found
And finally tonight, do you know how absent-minded we all are? Last year, we lost 500,000 laptops at airports. 60 million cell phones. So, is someone making a fortune on our forgetfulness? ABC's Alex Perez takes us to a kind of hidden treasure island. Reporter: It's that moment getting into a cab, realizing you left something behind. Cell phones, we lose 60 million of them each year. In hotels, 64 million items left behind. And laptops, 600,000 of them left at the airport each year. But where does it all go? It turns out your loss is someone else's gain. Welcome to lost treasure island, a warehouse just outside Denver, where four times a year, the city auctions off items found all over town. In parks, sports arenas, even public bathrooms. 200, now. Reporter: Strangers bid on the strangest stuff. Chainsaws, mandolins, even a tribal scepter. I have no idea what it is. Reporter: It's here we meet Aaron, lost treasure hunter. He made $1 million on the things you lost or left behind. He'll even pick up furniture on the side of the street. Oakleys. That Oakley could be worth $275. There's an opportunity for me to make extra money, I'm going to do it. Reporter: He looks for auctions just like this one across the country. His competition, other hunters, like Duane and Renee Nelson. We go for designer items that have aigher value that we can turn and burn, basically. They made $70,000 in profits last year. Someone has to benefit off of it. And we take it and use it to support our family. Reporter: So, next time you leave something behind, remember, kifinders, keepers. Losers, sweepers. Got something. Reporter: Alex Perez, ABC news, Denver. And if you want one of those bargains, we'll tell you online how to find a warehouse near you.
This transcript has been automatically generated and may not be 100% accurate.