Yeah of course you could DIY this or find your own subs much cheaper, but in the grand scheme of things, it's not that bad.

You get a finished and conditioned room, and it most likely added value to his house.

Unless he’s a commercial builder, I’d suggest he is wildly wrong about what is involved in properly pouring, leveling and making sure concrete has properly set in various weather conditions. And if you take a look at his post …