"the interesting lack of fundamental understanding by the general public about software and how complex and expensive it is."
The reason why many people have a good understanding of other complex stuff, like a car, is because they are able to tinker and service it. You can't tinker with the internals of Amazon.com. Without a frame of reference, there's no way to know how complex a system is.
The amount of stuff you need to sit down at your computer and try to build a "site like Amazon" is pretty trivial. In fact, all you need is a computer and a net connection.
You'll discover quite quickly that you can't build Amazon by yourself, but there's little barrier to entry (there's a huge barrier to completion).
The reason why many people have a good understanding of other complex stuff, like a car, is because they are able to tinker and service it. You can't tinker with the internals of Amazon.com. Without a frame of reference, there's no way to know how complex a system is.