This is what I've put together for $750. I added in a monitor and an SSD into the price. If you need Windows 10 or a mouse and keyboard, tack on an extra $120. If you don't need the SSD, scrap it and save $60.
CPU - i3-7100 $120; I'm probably going to get a lot of hate for this but realistically there is like maybe a 20% difference performance wise and $80 difference price wise when compared to an i5-7500. It's a solid dual core with 4 threads. Paired with a GTX 1050 ti, you can hit 40fps on Witcher 3 (An aggressive game) with high settings and 50+ on Medium!. Not bad considering what you're paying.
- https://www.amazon.com/gp/product/B01NCESRJX/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1
CPU cooler - Cooler master hyper 212 Evo $30; It does the job and it's cheap.
- https://www.amazon.com/gp/product/B005O65JXI/ref=ox_sc_act_title_4?smid=ATVPDKIKX0DER&psc=1
Graphics Card - GTX 1050 ti $160; Solid card, you don't need to worry about your CPU bottlenecking it either.
- https://www.amazon.com/gp/product/B01M6Y671T/ref=ox_sc_act_title_11?smid=ATVPDKIKX0DER&psc=1
MB - Gigabyte H110M $60; MB really doesn't matter that much, they're all the same. Just get one with USB 3.0's and you'll be good. This is a non-overclock and has 2 RAM slots @ 2400mhz. - https://www.amazon.com/gp/product/B0165YUDTM/ref=ox_sc_act_title_3?smid=A9RRFZDGAXG22&psc=1
RAM - 8gbs Ballistix Sport $60; 8gbs of 2400mhz ram, should be enough.
-https://www.amazon.com/gp/product/B00UFBZOVE/ref=ox_sc_act_title_10?smid=ATVPDKIKX0DER&psc=1
HDD - WD 1tb 7200RPM $40 OR SSD - 120gb Sandisk $60; If you want, scrap the WD and get the Sandisk or vice versa. You'll have to choose between speed and space here. Or you can do both.
SSD - https://www.amazon.com/gp/product/B01F9G414U/ref=ox_sc_act_title_8?smid=ATVPDKIKX0DER&psc=1
HDD - https://www.amazon.com/gp/product/B0088PUEPK/ref=ox_sc_act_title_9?smid=ATVPDKIKX0DER&psc=1
Case - Rosewill ATX Mid-Tower $50; Cheap and does the job, plus it looks kinda cool.
- https://www.amazon.com/gp/product/B01IT0TDY6/ref=ox_sc_act_title_5?smid=ATVPDKIKX0DER&psc=1
ODD - IF YOU NEED ONE. Which you might if you're gonna reinstall Windows 10 using a disc. $14
- https://www.amazon.com/gp/product/B00MOUBYDQ/ref=ox_sc_act_title_6?smid=ATVPDKIKX0DER&psc=1
Monitor - Viewsonic VX2257; 1080P, 2ms, HDMI, Freesync. I should of gotten this when I built my PC. $110
- https://www.amazon.com/gp/product/B018MYT3YO/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
PSU - EVGA 500w Bronze 80+; Solid brand. $40
- https://www.amazon.com/gp/product/B00DZ6R9GE/ref=ox_sc_act_title_7?smid=ATVPDKIKX0DER&psc=1
This should be a solid <$800 build. If you've got any questions or doubts, ask away!!