Order these in a restaurant, if you dare!

Beluga Caviar

These tiny, black fish eggs are considered a delicacy.

Caviar is available from various species of fish but Beluga, from the sturgeon, is considered the best and commands an astonishing  £4,000 per kilo.

It is usually served on blinis, with toast and hard-boiled egg or with a spoon straight from the tin.

Alba White Truffles

Previously rare black truffles are becoming more mainstream, but the white Alba truffle is still rare and highly prized.

This rather lumpy and unattractive looking ingredient is found in Northern Italy’s Piedmont region and sells for a staggering  £6,000 per kilo, versus the average black truffle’s  189 per kilo.

Blowfish

Otherwise known as the pufferfish or fugu, this Japanese favourite is famous for the risks carried by eating it.

Unless it is properly prepared, this fish can be fatally poisonous, leading to it being banned from menus within the European Union.

While it is available in other parts of the world, chefs receive special training and must obtain a licence to be able to sell it.

Consequently even a small fish costs around  £70.

Saffron

While saffron is expensive on a kilo per kilo basis at about  £800, a tiny amount goes a very long way so, unlike the other ingredients on this list, it is found in most supermarkets. 

4-5 will buy you a few fronds, which are used for their rich, golden colouring and distinctive flavour.

They are a key ingredient of the Spanish dish paella.