A tuna once sold this week for  £2.5 million, but you can get cans of tuna fish for less than $2 at the grocery store. So, what’s the difference? Bluefin tuna can be very expensive depending on where you buy it and which part of the fish you are eating. Business Insider spoke with the chef at Shoji in New York, Derek Wilcox, after the last Tuna sold for $1.8m to find out why the fish is so expensive.