I have two builds for you, the first one would be an entry-level gaming PC, and the second one will be a mid-range gaming PC:
PCPartPicker part list:
http://pcpartpicker.com/p/KKZZYJ
Price breakdown by merchant: http://pcpartpicker.com/p/KKZZYJ/by_merchant/
CPU: Intel Celeron G1840 2.8GHz Dual-Core Processor ($39.49 @ SuperBiiz)
Motherboard: ASRock H97M Anniversary Micro ATX LGA1150 Motherboard ($51.98 @ Newegg)
Memory: Kingston HyperX Fury Black 4GB (1 x 4GB) DDR3-1600 Memory ($22.69 @ SuperBiiz)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($46.89 @ OutletPC)
Video Card: EVGA GeForce GT 740 2GB Video Card ($77.98 @ Newegg)
Case: Deepcool TESSERACT WH ATX Mid Tower Case ($38.98 @ Newegg)
Power Supply: EVGA 430W 80+ Certified ATX Power Supply ($24.99 @ NCIX US)
Total: $303.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-10-05 03:17 EDT-0400
PCPartPicker part list:
http://pcpartpicker.com/p/Wr7Xcf
Price breakdown by merchant: http://pcpartpicker.com/p/Wr7Xcf/by_merchant/
CPU: Intel Pentium G3258 3.2GHz Dual-Core Processor ($64.99 @ NCIX US)
Motherboard: ASRock H97M Anniversary Micro ATX LGA1150 Motherboard ($51.98 @ Newegg)
Memory: Kingston HyperX Fury Black 8GB (2 x 4GB) DDR3-1600 Memory ($42.99 @ SuperBiiz)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($46.89 @ OutletPC)
Video Card: PNY GeForce GTX 750 Ti 2GB Enthusiast Edition Video Card ($94.99 @ Newegg)
Case: Deepcool TESSERACT SW ATX Mid Tower Case ($42.98 @ Newegg)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($44.99 @ Newegg)
Total: $389.81
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-10-05 03:17 EDT-0400