Fans of Ninja are scrambling to buy a five-star rated air fryer with more than 7,000 glowing five-star ratings as it's been slashed to less than £80 in Amazon's huge Black Friday sale.The air fryer is said to be so cheap and efficient to use, it has allowed Amazon customers to "ditch their ovens" and reduce their energy bills in turn. Normally £149.99, the 4-in-1 Ninja Air Fryer has been reduced to its lowest ever price and is now £79.The "bill reducing" Ninja Air Fryer AF100UK features four cooking functions.