The Del Monte Note is highly prized among currency collectors. It's a US$20 bill with a Del Monte sticker affixed to the paper before the bill was printed. The seal and serial number are printed over the label. In 2010 Heritage Auctions sold the bill to a lucky bidder for $396,000.
From Wikipedia:
The Del Monte note is a misprinted U.S. twenty-dollar bill on which a multicolored Del Monte sticker appears next to Andrew Jackson's portrait. The sticker became affixed during the printing process, prior to the application of the overprint but after the face print had been made. The result is a note with part of the seal and serial numbers printed on top of the sticker. In the paper money hobby, this error type is called a "retained obstruction." The vast majority of such errors do not retain the source of the obstruction but those that do sell for a substantial premium. The note is very famous among currency collectors and has appeared on the covers of industry magazines such as Bank Note Reporter and Numismatic News.
The Del Monte Note originated at the Fort Worth U.S. Treasury Department print facility. It was discovered by a college student in Ohio who received it from an ATM. The note had been preserved in uncirculated condition and was auctioned off on eBay for US$10,100 in 2003. On January 6, 2006, the note was auctioned for US$25,300 by Heritage Auctions of Dallas, Texas. The note was certified by Paper Money Guaranty in 2020. On January 22, 2021, Heritage Auctions auctioned the note for $396,000, the highest sale price for any error banknote.
Watch the exciting auction for the bill here:
[via Kottke]