ABC News' Alex Perez and Michael Koenigs report:

It's that moment travelers dread: scrambling through the airport or hopping out of a cab and realizing they've left something behind.

So where do forgotten items - cell phones, jewelry, snowboards, wallets, and even a chainsaw - all go?

The lost becomes someone else's profitable found.

Aaron Lapedis calls himself the Garage Sale Millionaire. He made his first million before he was 25 by buying low and selling high.

"If there's an opportunity for me to make a little extra money, I'm going to do it," he said. "It's junk to them, but it's a hidden treasure to me."

He bids on lost stuff at a warehouse auction just outside of Denver. The stuff is found all over town and sold off at the auction by the city, which is looking to inject some cash into their coffers.

"The average auction is about $60,000. That's $60,000 for things that are just here gathering dust," Lapedis said.

During a recent visit to the auction, Lapedis examined silverware, but he had some competition.

Duane and Renee Nelson, who operate a small business called Thrill of the Hunt Retail, made $70,000 last year.

"Someone has to benefit off of it and we take it and use it to support our family," Renee Nelson said.

Lapedis was outbid on the box of silverware by a guy who paid $750.

The Nelsons had much better luck using eBay to resell the items they had purchased.

"From the $400 we spent, we're up $200 in profit," said Duane Nelson.

Lapedis shared the following tips:

1. Timing is everything. He looks for auctions early in the year just after the holidays because people are having credit card hangover.

2. Attend auctions on rainy days or during big sporting events because there will be fewer people to compete against.

3. Bring your smartphone so you can look up resale values on the spot.

4. Check your local City Hall for information on auctions.