I'm currently playing tsw on Xbox because my PC sucks. If I even load up Train Sim World CSX Heavy Haul on it it crashes.
Just look for any prebuilt PC you can buy within your monetary limits. Grafics Card: Anything with at least a GTX 1060/2060 i would say is a usable for TSW on FullHD. The better performance at a good price is with the GTX 1070/2070 and i would recommend that for any higher resolution than FullHD. For the Radeon cards i am not up to speed with the models, so cant say anything to that. The graphics card is really the most important thing in a gaming computer, so spend your money there. Other components: Some Intel Core I5 8xxx or 9xxx CPU is enough. Core I3 will get a bit tight. I7 is better and I9 is overpowered for gaming. At least 16GB RAM of any speed. Any SSD as storage with 512GB or 1TB. Or a small SSD and a big Diskdrive for the games. Once the game/world is loaded, an SSD doesn't speed it up much. I don't know how much they want for such a PC, but i would say from 800$€ (or whatever equivalent) upwards will give you something descent. That's without accessories like a display, keyboard, whatever you want more...
I'm gonna contradict what Sintbert stated and recommend you build your own. I have bought my share of pre-built gaming PCs in the past and have been underwhelmed at best. Figure out what you want to do with your PC and determine a budget; from there you can get a basic parts list going. Take your time, practice due diligence and do your research. If you're serious about this hobby, invest your time into it and you'll have yourself a machine that will meet or exceed your expectations and last you a long time. With a custom built PC, you'll spend your money wiser as you will know exactly what is going into that machine! Those pre-builts come with a lot of cheap parts. If I may recommend a good website to utilize, it would be this one: https://pcpartpicker.com/ That is where I started when I decided I wanted to build my own. I didn't know anything about PC building and learned so much from the community here. They have a lot of great tools to use and their own forum section which is very helpful.
Building you own computer is always nice, but it requires knowledge, which by the title of this thread i assume isn't there. So building your first PC will be rather time consuming to develop that knowledge. Also in the range of cheap/low-end gaming PC's you don't safe much by building it yourself. From experience i can say you safe about as much as it costs a cheap PC-builder to screw it together.
I didn't say it would be cheap. I said at a good price. A good price varies depending on what your dealing with. Though you are right I don't know the best about PC's there's always a good time to start.
Whichever route you decide, pre-built or DIY, do your research. Determine what your budget is, what you want want to do with your PC (gaming,streaming,editing) and what your expectations of it are (FPS, resolution, graphics settings). Sintbert is right to state that this process can be time consuming but remember, this is an investment. Even a low end pre-built is gonna run you a good chunk of change so you wanna make sure you know what you're putting your money into. Take the time and learn .. you'll be better equipped to decide how to spend your money because of it.
Gaming PC is a very loose term and prebuilt ones can be a minefield if you don't know what you are looking for. If you search eBay, for instance, you'll get a whole bunch of "Gaming PC'S" which are far below the games minimum requirements and are listed to part the inexperienced PC buyer from their money and often have GPU's like the GT 710 which weren't designed to run modern or graphical demanding titles. That's why it's best to ask others for the parts they should be looking for in a prebuilt machine that way you don't end up with hardware which is overpriced and not up to the task.
Well, that depends on a multitude of different things. What resolution do you play at? Are you looking for a 30fps or a 60fps experience? Are you looking to play at low or the max graphical settings? Do you plan to stream the game?