You’ve hit the jackpot if you have a hardcover first edition of the 1997 edition, with a print line reading "10 9 8 7 6 5 4 3 2 1" and the author credit as "Joanne Rowling" (rather than JK Rowling) - these can be worth up to a whopping $40,000 (£31,800).
Remember these miniature dolls and their cute carry cases from the 1990s? While not all Polly Pocket toys are worth a whole lot, some sets (especially unopened) are being sold for up to £1420.
Look in your old toy box for the original Alice in Wonderland or Little Mermaid sets from 1996, or the Birthday Surprise set from 1994 - this recently sold for £870 on eBay.
Vintage band and concert t-shirts
All you have to do is walk into your local Primark to see that there are loads of mass-produced band tees at the moment, but the vintage originals can be worth a good lump sum.
Have a look through your old t-shirt pile to discover any hidden gems. In the last few years, a Led Zeppelin shirt has sold for £9,400 (even with holes in it!) and a Run DMC tee for an impressive £6,400.
This classic toy has spanned generations and new sets are still being released today, but the Lego collectors market is big business. Some of the highest value sets are those from the adult market, which Lego expanded into in the early 2000s. The Ultimate Collector’s Series Millennium Falcon can sell for up to $15,000 (£7,645).
One of the most highly sought-after games is the Metal Slug original production run for the Neo Geo, with sealed copies selling for up to $2,850 (£2,250). Donkey Kong Country 3 for the SNES is selling for up to $1500 (£1,185) and sealed copies (with the original black label) of popular Final Fantasy X for PlayStation 2 are going for around $300 (£236) - but opened copies only rake in about £10.
Image source: Amazon
It’s time to root through your old record collection, as a lot of pristine condition LPs are now highly desired and go for a sizeable sum. Some albums that could bring you in a pretty penny are the Spiceworld album (mint condition copies go for up to £200) and the 1995 Smashing Pumpkins album, Melancholie and the Infinite Sadness, which has sold for up to £500.
Most Pokemon cards floating around will hold little to no value, but a rare few could be enough to rake in £1000s. Aside from rare cards like competition-winning prizes, a few in any regular fan’s collection could be worth a pretty penny. Some of the most valuable include a first edition Charizard Shadowless (up to £5498), Blastoise first edition (up to £1,298) and a Venusaur first edition (up to £400).
Disclaimer: All information and links are correct at the time of publishing.