From Pokemon cards to film props, collectibles come in all shapes and sizes.
But what are the most expensive pieces of memorabilia out there? And would someone really pay more than $8 million for a stamp?
Find out with our definitive list of the top ten collectibles in the world.
Stamp: $8 million
The 19th century British Guiana one-cent magenta stamp sold for a staggering US$8 million at an auction in New York in 2014.
Measuring 2.5cm by 2.5cm, the stamp is printed on magenta paper and bears a three-masted ship.
It was the fourth time the stamp set a world auction record and, according to Sotheby's auctioneers, "has been heralded as the pinnacle of stamp collecting for more than a century".
Film poster: $690,000
The international version of the poster for the 1927 science-fiction film Metropolis was sold in 2005 for US$690,000.
Designed by graphic artist Heinz Schulz-Neudamm, there are only four known copies in the world.
Set in a futuristic city full of skyscrapers and steel, Metropolis is often referred to as the first ever full-length science fiction film.
Pokemon cards: $100,000
Only 39 of these Pokemon Pikachu Illustrator cards were ever made. The card is the only design to have "Illustrator" written on it rather than "Trainer" because it was awarded to winners of Pokemon illustration contests in 1997 and 1998.
The eBay description reads: "This card is the Holy Grail of Pokemon... The illustrator is the most valuable card in the hobby."
Comic book: $1 million
A 1938 edition of Action Comics No. 1 was sold in February 2010 for US$1 million.
Originally costing just 10 cents, the front cover of the issue shows Superman lifting a green car over his head. John Dolmayan, a comic book dealer who is also drummer for rock band System of a Down, said at the time: "It's considered by most people as the most important book. It kind of ushered in the age of the superheroes".
Sports memorabilia: $4.4 million
A New York Yankees shirt shirt worn by legendary baseball player Babe Ruth was sold for a record-breaking US$4,415,658 in 2012.
Ruth is considered by many to be one of the greatest players of all time and his old "jersey", as they say in America, took the top spot from the "Bible of Basketball" - a two-page document containing the "founding rules" of the sport - which went for $4,338,500 in 2010.
Coin: $10 million
The "Flowing Hair" silver dollar coin was bought by a collector for US$10 million in 2013 and is believed to be the first US dollar ever minted.
The coin, which went on display in Britain for the first time earlier this year, was one of 1,758 silver dollars struck on October 15, 1794, on a hand-turned screw press at the Philadelphia Mint. Many experts even believe it is the first American coin ever struck.
Lego set: $4430
At US$4,430, the Ultimate Collector's Millennium Falcon is nearly $2,000 more valuable than its nearest challenger, the Taj Mahal set.
The Star Wars-themed set first hit shelves in 2007 at a retail price of $499.99 and comes with minifigures of Luke Skywalker, Princess Leia, Chewbacca, Obi-Wan Kenobi and Han Solo.
The most expensive postcard ever is also believed to be the world's oldest. It was sent from a Fulham-based writer named Theodore Hook to himself in 1840, according to Guinness World Records.
The postcard was then sold to Latvian collector Eugene Gomberg for £31,758.75 (US$45,583) at the London Stamp Exchange auction in the UK in 2002 and is believed to predate all other surviving postcards by around 20 years.
Film prop: $4.6 million
According to a study by eBay Entertainment Memorabilia, the most expensive film prop ever is Marilyn Monroe's iconic white dress from "The Seven Year Itch", which sold for US $4.6 million in 2011.
The ivory dress is, of course, best known for its starring role during Monroe's encounter with an updraft from a subway grate in New York.
It just pipped Audrey Hepburn's Ascot dress from My Fair Lady ($4.5 million) to the title, while James Bond's Aston Martin DB5 from Goldfinger went for $4.4 million.
For rare music memorabilia fans, it does not get much bigger than The Quarrymen. Formed in Liverpool in 1956 by a young John Lennon, The Quarrymen were the precursor to The Beatles, eventually evolving into legendary band in 1960.
According to an NME study, the 1958 original version of The Quarrymen's track 'That'll Be The Day/In Spite Of All The Danger' is worth an estimated £100,000. It's also worth noting that a 1981 reproduction of that original - worth £10,000 - is second on the list of the world's most expensive records.