For the same set-up?
£100-£130 for a GPU block like that one.
The Alphacool pump/block is getting hard to find now, so not many discounts about. Looking at £60-£70 for one, unless you get lucky. As well buying the whole AIO and splitting it down now TBH (~£75).
The radiator (if it's the one I think it is; I haven't checked) is £49.99 on OCUK.
The 90° rotary fittings are £6.99 each. He's using seven of them.
Similar T-Splitters are £7.99. He's using two.
Then there's compression fittings. Maybe £4 or £5 each? Six of those.
And you still need to add tubing, coolant, and any tools you may need.
Could be £350, easily.
It isn't something anyone is likely to do unless they have the parts already. Expensive, difficult, and potentially not even all that great (time will tell).