Best case under £50?

Vic 40

Titan
Ambassador
I couldn't help messing with your build,

PCPartPicker part list

CPU: AMD FX-8320 3.5GHz 8-Core Processor (£109.62 @ Amazon UK)
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard (£68.87 @ Aria PC)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£42.99 @ Amazon UK)
Video Card: Gigabyte Radeon R9 280X 3GB Video Card (£224.60 @ Amazon UK)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply (£49.13 @ CCL Computers)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) (£70.30 @ CCL Computers)
Other: Memory (£54.99)
Total: £620.50
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-12-30 16:51 GMT+0000)

A better gpu,a slightly worse cpu for just a little bit more.

I would also buy the next cooler,
http://uk.pcpartpicker.com/part/zalman-cpu-cooler-cnps10xoptima

For cases,
another under £50,
http://uk.pcpartpicker.com/part/zalman-case-z11plus
slightly above but good cases,
http://uk.pcpartpicker.com/part/fractal-design-case-fdcacore3000usb3bl
http://uk.pcpartpicker.com/part/enermax-case-eca3261b