Price and Specs. For new gaming PC

Hello all, I'm considering fully switching from console gaming to PC gaming. I have an outdated PC a friend helped me build from exactly 10 years ago, and it has never been upgraded. I currently have a Nintendo Switch and Xbox (360, One, and most recently Series X). I did this mainly because I liked physical games, such that I have kept boxes, manuals, and discs for my games. However, I have been getting more and more frustrated with console gaming as the years progress and am thinking of switching to fully PC, including emulation up to Switch of older game systems. I know nothing about building a PC, the one I had in college was for games technically but was not top of the line even then, and I mostly used it for torrenting, CAD modeling, and old emulation (up to Nintendo 64 at the time). I'm thinking of transitioning that fully to a NAS if possible as I build out my media library, and build a new one from scratch for gaming. Any advice on what a price range would be and components to look for would be appreciated! I see secondhand builds on Facebook marketplace or similar but don't have a good feel for if they are even good deals or not. For what it's worth, I will probably need new everything (hardware, case, and peripherals like mouse, keyboard, and monitors). So, if anyone could help guide to me what a good price I should be expecting would be and some benchmark specifications that I could keep an eye out, that would be lovely.

Edit: for what it's worth, I generally play games a few years after release when they go on sale, unless they came up on Xbox game pass or I received it as a gift to play. Additionally, I had an Oculus Rift hooked up to my PC but it struggled with many things on it, so I plan to upgrade that at some point with maybe the Valve Index system. That doesn't need to be an immediate buy as I'd rather my money go into the computer hardware itself first.