Depending on what your previous computer was, you might be able to reuse a lot of parts.
I'm thinking about the tower case, the keyboard, mouse etc...
Meaning the only real hardware you need to buy is:
- a CPU
- a motherboard
- a power supply (might not need a new one, but it's safer to switch to a new one)
- a video card
- some memory (RAM)
Given your real-life constraints you mentioned, I guess it is important to know if you are able to build a computer by yourself, or if you prefer an "all-in-one, ready-to-use" computer ?
Concerning the choice of hardware, for P3D the community tends to agree the best choice is an Intel i7 CPU coupled with an NVidia video card.
The Intel i7 can use the hyperthreading, which works quite well in P3D (no additional FPS at all, but less blurries of the ground textures). I don't know the current generation names though, so I hope someone else can bring more precise recommendations and prices.
Concerning the video cards, the current NVidia generation is the 10xx (thousand something). The xx is the level of the card, described as follow:
- less than 50 = home computer for multimedia (movies, office work etc...). Not for gaming.
- 50 = low end gaming card, the cheapest choice but still with acceptable performance in games
- 60 and 70 = middle range, quality/price balance. These are usually the best choices for the average gamer. Of course the "70" is superior to the "60", but also a little bit more expensive.
- 80 and above = high range, ultra performance. These are also the most expensive ones, obviously.
IF you are not looking for virtual reality helmets, then I would recommend you a 1060 or 1070 video card. If your budget is too low, I would recommend you to look at the previous generation, the 970. I have one and it works very well in P3D. The performance in XP11 is not bad either, but in both cases the performances are limited because my CPU is too old (i7 960, it's more than 5 years old...).