Is this overpriced compared to what you could build yourself? Well of course it is, you are working for free when you build a computer, but these people aren't. This looks like a competent prebuilt for the PC gamer that doesn't have the skill, time, or desire to roll their own build. And you get some benefits that might make it worthwhile for those that are less computer literate than people that post on a hardware enthusiast news site.
For example, a 1 year parts, 3 year labor warranty on the whole computer, not just the individual parts, is useful for a lot of people. If it breaks, send it back. If you buy it with a good credit card, that becomes 2 years parts, and maybe 4 years labor. As is a Windows installation with chipset and GPU drivers preinstalled. As is a guarantee that the parts were tested together. There is nothing worse than the fear of putting everything together and worrying about whether one part will prevent the whole machine from booting, leading to hours of triage. The parts selection actually looks decent, too. Of course it's not the highest end PSU or motherboard, but it's at least specced right and can overclock out of the box.
I have played around with the idea of building computers on the side as a business. It's daunting to think about being on the hook for a faulty component, or paying myself a fair wage while building, testing, and installing the computer. I came away with something like $200 minimum and 20% of the total components cost, whichever is higher. And I wouldn't even be giving a warranty or anything. There's a reason it makes sense to learn this stuff and build it yourself as a hobby. You're looking to fill your time with a hobby. For everyone else that just wants a fancy-looking computer with adequate parts, this will do the job.