There's more to it than you might think. There are basically two contenders making the products we use: KEL and AWC. Both companies have valid patents using two different technologies, "plastic" and "elastic". Both organizations are actively seeking to enforce their patent and defend their technology. So, we are paying a premium for their legal battles.
Detailing clay is not a product mined from the earth. It is manufactured from synthetic materials. A lot of money went into the original research of "plastic" clay in Japan. AWC imports plastic clay from Japan made under their patent design (may begin making it in the USA soon, if not already). KEL developed the "elastic" clay technology and manufactures it in the USA for its customers.
Give the time saving and results provided by detailing clay, I think the cost is justified. Like every other technology, the price will adjust with demand.
db