Tennessean Michael Sparks strolled into the Music City Thrift Store in Nashville last year, a normal part of his weekly agenda. He picked up a candelabra, a set of salt and pepper shakers and an old copy of the U.S. Declaration of Independence. He paid $2.48 for the latter item, a "standard price" according to store manager Kay Boner.

The "standard price" was altered significantly a year later when Sparks sold the document to a Utah investment firm for $477,650, causing a national stir.

The copy happened to be one that John Quincy Adams commissioned William Stone to make in 1820. Stone finished printing 200 copies of the famous declaration in 1823. The location of only 35 of these valuable historic documents was known until Sparks punched the number up to 36 with his thrift store find.

"I've seen Declarations of Independence in thrift stores before," said Sparks. "This one was so beautiful I thought it was an engraving. I look for things that have quality to them."

Two days before Sparks' lucky find, another Tennessean possessed the article, hanging unnoticed on his wall in the garage. Stan Caffy's wife asked him to clean out the garage and ditch all the junk he'd acquired through the years. He reluctantly took the old Declaration of Independence off his garage wall and donated it, along with other odds and ends, to the thrift store. He bought it for $10 at a yard sale 10 years ago.

"It just doesn't pay to keep a clean house," said Sparks of Caffy.

After diligent research and an assessment from Raynor's Historical Collectible Auction in North Carolina, Sparks' find was proven authentic. Don Etherington, who worked on conservation of the original Declaration of Independence in the '90s, performed the conservation work for the newly acquired artifact.

"They removed the document from a canvas carrier, remoisterized it and removed the varnish from the face," said Bob Raynor, president of the historical collectible auction. "Because of the varnishing the ink remained dark."

Because of the dark ink this copy is one of the best preserved of its kind, according to Bray-Conn, the Utah investment firm that purchased the declaration.

Sparks sold the artifact through Raynor's Historical Collectible Auction for $477,650 to Bray-Conn. The price was more than Sparks and everyone else involved imagined.

"I was delighted," said Raynor. "I assumed it would sell for $300,000 to an institution. We broke a world record."

The previous highest price for a William Stone copy of the declaration was $397,000, making this new buy the highest in the world by almost $100,000.