When a new market begins it is usually higher priced and it is expensive and accessible only to the rich. 

As it gets more widespread and more market players start in entering and they start reducing prices, it is imperative that the only way to survive is rock-bottom prices at humongous volumes. 

Dirt cheap prices can be introduced when the general public has got involved in these kind of purchases. 

Such is the story of stock market brokers over the last century.

 First only the rich could afford, then it was $40 per trade, and now it's in cents with online brokers.