if I walk into my local Micro Center and try to build a comparable machine, I'm getting dangerously close to $3,000.
I have a massive issue with this claim. Just what kind of parts (comparable in performance) do you choose to bring it up to that point?
This claim sounds bogus. Send the pcpartpicker list.
At most, you should end up at like 1500$, but only if you spend on looks or are clueless of what you're doing.
It's really not difficult to make a PC with similar or possibly better performance at that price.

My only complaint was that you have to really try to make a similarly-priced build cost $3k, I don't know what you would even put there to bring the price that high up.
Other than that, yeah, Steam Machine costs about what a regular PC would cost.