There are 34 billion Pokémon cards around the world and some of these could be worth up to £1.2million.
Financial website Money.co.uk analysed all the Pokémon cards sold on eBay to see which ones could earn the most.
The most valuable card on the market is on sale for $2.4million Australian dollars, equivalent to £1.2million.
Plenty of other valuable cards are also selling for tens of thousands of pounds.
What are the most valuable Pokémon cards?
1) Pikachu - £1.2million
The ‘Japanese Old Back Pokémon Trophy Card NO.2 Neo Spring Battle PSA 9 Pikachu’ card is up on eBay for a huge price.
The card was made in 2001 and is very good condition.
2) Kangaskhan - £350,000
Sellers are on the hunt for the ‘PSA 10 Trophy Kangaskhan Parent & Child Tournament 1998’ card and are willing to pay some serious sums of cash.
3) Joint place between Blastoise and Venusaur - £185,868
EBay sellers are asking for almost £200,000 for two separate cards.
A ‘1st Edition Japanese Base Set No Rarity Blastoise 1996 PSA 10 Mint’ and the ‘1st Edition Japanese Base Set No Rarity Venusaur 1996 PSA 10 Mint’.
4) Rayquaza - £73,062
Pricing at the same cost as a luxury car, the ‘EX Deoxys # 107 Gold Star Rayquaza Holo PSA 10 Card’ card is on offer to be snapped up by fans.
5) Ivysaur - £54,797
The rare ‘PSA 10 ITALIAN Ivysaur #30 1st Edition GEM 10’ card is pricing near-£55,000.
Despite Pikachu featuring on the most valuable card, it is not the most valuable character overall.
What are the other expensive cards?
Cards that feature the Starly monster (a kind of bird Pokémon) are the most expensive cards, worth a median price of £399.51.
Those that have the character of Bidoof on them are selling for around £285 on average.
Charizard cards are pricing at £150 and Lugia ones at £149.99.
Cards with the character Umbreon on them are going for £142.
How do you know if you’ve got a valuable card?
You can check the bottom of each card to see roughly how rare it is.
A circle means common, a diamond means uncommon, a star means rare and a white or gold star means ultra-rare.
Holographic and first edition cards are also typically worth extra.
To see how much your cards are worth, you can check eBay to see how much those cards are going for on the site.
Limited-edition cards that collectors can only get by going to special events or through competitions, will also be more valuable and expensive.
However, you have to take into account hidden costs such as shipping fees, tax liabilities on sales and storage costs.
Storage is crucial to keeping cards in ‘mint’ condition and preventing them from any damage.
What is Pokémon?
Pokémon is a series of computer games and collectible cards.
It focuses on a fantasy world where people catch and train cartoon monsters for sport.
The Pokémon card game launched in 1996, and 34.1billion individual cards have been sold across the globe.
What’s been said?
Money.co.uk finance expert Salman Haqqi said: "Pokémon cards have rapidly grown as a popular alternative investment.
“The nostalgia combined with the iconic characters have certainly recaptured the imagination of many people - so much so, they are willing to spend thousands, if not millions to ‘catch them all’."
A version of this article originally appeared on NationalWorld.com