Building a gaming PC under $200 is extremely challenging, especially considering the cost of components necessary for a decent gaming experience. I have Build a $200 Gaming PC, here are components I have used:
Graphics Card: MLLSE RX 580 – $60
Motherboard Kit (including CPU & RAM): SZMZ X79 G-A LGA 2011 Kit – $50
CPU Cooler: Aigo ICE200 Cooler – $10
Storage: KingSpec 512GB Gen 3 SSD – $20
Power Supply & PC Case: Rosewill FBM-X2-400-HELIX – $50
Now, If you want to the benchmarks of this PC, you can see on my Blog: Budget Gaming PC Build Under $200