I agree on the mobo blocks, not worth it, they just dump heat into your loop and create a lot of restriction. You dont need 2 rads for a cpu and gpu loop, a decent 360/480/420 will be plenty. A loop including a gpu block can be done for about £250 but you'll more than likely spend over £300 as you won't buy the cheapest components. My build came in at about £370 and i bought a few items from the members mart, from log in my sig
Ek Supreme Hf full Nickel £50
Ek fc5870 acetal nickel £65
d5 vario £30 (mm)
hwlabs sr-1 420 £80
ek multi 250 £15 (mm)
8xTFC ½id ¾od 45 rotary £20
8xTFC ½id ¾od compression fittings £24
3m ½ id ¾ od Primochill LRT blue £12
3xYate Loon D14SL-124UB £18
4xYate Loon D12SL-124UB £18
Scythe Kaze Master £27
Silver kill coil £4
Distilled water 10 litres £10
Total £373