Korean tea is roasted just like Chinese tea as they adopted that tradition from Shila period. One assumed a monk who studied in Zhejiang, China brought tea tradition into Korea as it tastes a lot like Zhejiang's buddhist mountain and tea, Jing Shan Cha.
As quality matters, Korean's annual production of tea is uncomparable to Japan or China, so the price.
Now I am gonna be bold to say this, my acquaintance who is a tea seller once said that(we are both Koreans). If you count quality to price, this fomula can be made. 4:2:1 - 4 is Chinese tea 2 is Japanese tea 1 is Korean tea. Of course higher number is good one.