I can say from experience, having just finished my first, every simple block, that commercial blocks are priced the way they are because:
a. People will buy their blocks at the price they choose
b. The machines required to make & human effort to test each block costs a whole lot (machines something like $100k)
c. It takes a long time to create a design that can be made for that price that will perform better than the last model
d. Even with super-expensive machines, it still takes a long time to make these blocks
If you think new blocks cost too much, then look around for last generation or used blocks, and if you really want to buy someone's homemade block, look on ebay or the classifieds for old ones, which probably took the person at least 10 hours to make, more if they lapped it.