CTR stock (which is what's on the Spike's lower he referred to) is over $100.00 and that does not include the receiver extension tube, buffer or spring.
At the end of the day it all depends on what he defines as "cheap". The Vulcan lower we have on sale @ $269.99 is about as cheap as it gets. Personally if I was building a .22 AR it's a great option... better than the COLT or S&W .22 rifles that also use polymer receivers and that are NOT compatible or changeable to other calibres... and especially better if I was planning to use the lower occassionally with an inexpensive .223/5.56 upper. If I was building a .223/5.56 rifle and wanting to get quality components for a serious build then I would not choose to use the Vulcan lower... because I don't base my buying decisions on price alone.
If what you want to do is build the cheapest, lowest cost rifle using the least expensive materials possible, then don't expect to get high quality brand name components.
The Vulcan lower we offer is a low price option for people... it uses a quality RRA parts kit, but the receiver, stock, buffer, spring, etc. are all low price options to get the end-user the lowest price possible. As you change components to higher quality you also increase the price of the assembly.
Pretty simple economics.
Mark