PCPartPicker part list:
http://uk.pcpartpicker.com/p/tvfmmG
Price breakdown by merchant: http://uk.pcpartpicker.com/p/tvfmmG/by_merchant/
CPU: AMD FX-6300 3.5GHz 6-Core Processor (£73.96 @ Scan.co.uk)
Motherboard: MSI 970A-G43 ATX AM3+ Motherboard (£46.76 @ Scan.co.uk)
Memory: Corsair Vengeance 4GB (1 x 4GB) DDR3-1600 Memory (£32.88 @ Scan.co.uk)
Video Card: XFX Radeon R9 280 3GB Black Edition Double Dissipation Video Card (£179.14 @ Scan.co.uk)
Case: Corsair 300R ATX Mid Tower Case (£59.16 @ Scan.co.uk)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply (£37.79 @ Scan.co.uk)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£11.51 @ Scan.co.uk)
Total: £441.20
Prices include shipping, taxes, and discounts when available