When it comes to collectibles in the United States, there are few things to rival the passion and depth of sports memorabilia. It's estimated that the market in the US is worth around $1 billion a year.
But whilst Baseball has witnessed world record prices at auction in recent years, the world of American football remains relatively undervalued.
After all, the national football league has been around for over 90 years and remains the most attended domestic sports league in the world, with an average of 67,509 fans attending every game in 2009.
And the sport is slowly beginning to reach an increasingly global audience, with one NFL game now scheduled for Wembley in London, every season.
Furthermore, with an audience of 106.5 million tuning in to Super Bowl XLIV the value of collectibles attached to players like Eli Manning, are underpinned by this huge group and will only increase in time.
With these figures in mind, here are our top 5 collectibles from the world of NFL.
Worn during an encounter with the Seattle Seahawks, the match saw Favre lead Green Bay to an impressive five touch downs.
Today, Favre continues to play Minnesota Vikings, but many of his greatest moments came in the green and gold of the Green Bay Packers.
Recognized as a true hall of fame player with nearly a dozen different NFL records to his name, this used jersey sold for $11,950 back in August 2010.
Once Favre retires, this value could increase sharply.
4. The 1957 Jim Brown Rookie of the Year Trophy
Jim Brown is widely regarded as one of the greatest running backs in the history of the National Football league. Back in 1957, he was at the start of what would prove to be an illustrious career and was the unanimous choice for 1957 Rookie of the Year with 942 rushing yards.
Measuring 15 inches in height, this trophy came up for auction in October 2007 and was widely considered to be one of the major pieces of the Football Hall of fame. It sold for $31,070.
3. Dan Marino's 1985 Super Bowl XIX Game Worn Helmet
Whilst many collectors will remember Dan Marino for his extended cameo appearance in Jim Carrey's smash hit comedy "Ace Ventura: Pet Detective" he did also happen to be one of the true greats of American football.
But whilst his careers stats showed his superb passing yards and touchdown completion record, a Super Bowl victory eluded him.
In May 2007, his match worn helmet from Superbowl XIX, when Marino came closest to the coveted prize with the Miami Dolphins, sold at auction for $33,460. Regarded as the finest Marino helmet to ever be offered in public sale, this is one investment piece with great potential for the future.
Whilst Baseball cards continue to set astonishing prices at auction, some extremely rare American football cards offer similarly impressive returns at auction.
This 1952 complete set was regarded as one of the most beautiful issues of football cards ever collected, topping many a hobbyists' wish list. Amongst the collection, the 144 Lansford card is arguably the rarest.
During packaging at the factory, many suffered disproportionate wear and poor cutting and were discarded before release, making the card amongst the rarest on the market.
Famous rookie names like Donovan, Marchettis, Matson and Robustelli also featured alongside more established names from the golden era of the sport.
The set sold in May 2005, for an impressive $59,750
1. The Original Plaster Cast used for the Heisman Trophy#
Conceived by New York's Downtown Athletic Club, as college football's highest award back in 1935, the Roman Bronze Works were hired to create the trophy which became synonymous with excellence.
The trophy was awarded annually to the most outstanding college player of the year and has been won by the likes of Paul Hornung, Marcus Allen, Barry Sanders and Roger Staubach.
The dynamically sculpted award today represents the ultimate symbol of individual athletic achievement in the game .
In October 2008, the maquette used to cast each and every one of the first 40 trophies of the era sold for $89,625.
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