Yes, Cappadocia is cheaper than Istanbul. Istanbul is the largest city in Turkey, with around 15 million people, and Cappadocia is a rural desert region with smaller towns and lower prices.
We recommend Cappadocia if you’re on a budget, as accommodation, restaurants, and transportation are cheaper. Also, most activities in Cappadocia are free and happen outdoors, while you’ll spend more in Istanbul at places like bars, museums, and theaters.