Building
can be cheaper than buying a pre-built, you have to be savvy though. For instance, I bought a used GPU that was a generation old, because I mostly play MMOs and RTS games, therefore I saved about 300 right there. I also didn't buy Windows (100 right there) and instead got a Windows code off a customers old computer they dumped off at our store

I bought my RAM when it was on sale for the lowest I've ever seen.
My coworker helped me assemble and choose the parts, he's much smarter than I. But now that he helped me do it, I realize it's fairly simple. Also, most electronics stores (Fry's, Microcenter) will usually assemble it for you for 80ish bucks, not including any OS or software installs.
A very important thing to realize is what your minimum needs are; do you play new FPS games, or stuff like PUBG? You'll need high end gear, and a good GPU comparison chart such as the one on Tom's Hardware website will tell you equivelencies between brands/models. Compatibility of any parts you use is also a priority. A newer motherboard won't be able to use DDR3 RAM for instance, you'll have to use newer DDR4. Motherboards have chipset compatibility which dictates which brand and generation of CPU you can use. GPUs are universal and any normal motherboard can take at least one PCI-e gpu (the format of any modern desktop gpu).
A great website for building your PC vision is
https://pcpartpicker.com/
They usually compile the best prices from across the web for any parts, and their cart will tell you if you're using incompatible parts, so it makes things extremely simple. Or remind you that hey! You're cpu choice doesn't come with a cooler, you should get a cooling system of some sort! (Most AMD seem to come with cooling, Intel rips you off and leaves it out and STILL charges more, but they have better clock speeds and temperatures for high end gaming, so it's a trade off.
I think that site I linked has guides on building as well, so it's a great place to start.
I'll say this, a PS4 is 3-400 bucks right? Can play anything built for it. PCs are much more expensive and much more specific. But, a PS4 comes with a low end cpu and built in gpu, neither of which come anywhere CLOSE to the power a PC can have, and thus, the graphical output a PC can have. Also fun tidbit, the Xbox One and PS4 use the exact same cpu, gpu, ram... they're the same hardware wise, all that changes is the OS. Kind of silly lol. No difference anymore!
I spent 850 on building my PC, and that was with a lot of cheating, such as what I mentioned in the first paragraph. A decent modern GPU will run you at least half that, right up front. I think prices have dropped a bit, but the point still remains, that the GPU alone will cost you as much as your PlayStation

BUT! A good PC can do anything and play anything you want. You can have much better graphics. You can play games you never even knew existed. You can watch porn on it, use it for music, it's a complete multimedia unit obviously.
It's up to you whether you're willing to essentially blow a grand on that lol.