This is where i would spend the cash. I have left £50 of the budget to be spent on fluid, angle fittings or changing parts for slightly more expensive parts more to your aesthetic preferences.
YOUR BASKET
1 x
EK Water Blocks EK-FC R9-290X - Acetal £79.99
1 x
EK Water Blocks EK-Supremacy Clean CSQ - Acetal £49.99
1 x
EK Water Blocks EK-CoolStream PE 360 (Triple) £49.99
1 x
EK DCP 4.0 Pump (12v) £39.98
1 x
EK Water Blocks EK-CoolStream PE 240 (Dual) £39.95
1 x
Aqua Computer Aqualis ECO 100ml with Nano Coating £34.99
2 x
Corsair SP120 Performance Series High Pressure - Dual Pack (CO-9050008-WW) £22.00 (£44.00)
1 x
Corsair SP120 Performance Series High Pressure - Single Pack (CO-9050007-WW) £10.08
2 x
Primochill Primoflex Advanced Tubing 13/10 - Clear £5.99 (£11.98)
12 x
EK Water Blocks EK-CSQ Fitting 10/13mm G1/4 - Black £2.99 (£35.88)
Total : £406.40 (includes shipping : £8.00).
If you dont know what to spend the remaining cash on, you can go for nickel versions of the above blocks (an aesthetic option), monsoon fittings (another aesthetic option) or a different high end block (they all perform practically the same as each other when you get to the £50 mark, so really another aesthetic option). I included a tube reservoir, as a bay res will limit the space for radiator if you plan to cut the front up to fit one there. If you cant fit a 360mm, i would look at external DVD player to make more space too, as these Hawaii GPU's do appreciate the extra headroom.
If it was my money the remaining £50 would be spent on:
1.Fluid from Mayhems or Koolance (a must lol)
2.£15 on a few rotary angle fittings to connewct eh CPU and GPU cleanly without loops of tubing
3. external DVD player, so you can fit maybe a bigger radiator in the front
4. Spray paint for the silver bits of the case and some pre-braided cables
5. If you dont mind adding more cash, you can go for a D5 pump, though i will say that it is an expensive upgrade considering you will gain no tempereture performance
Most of the gear i chose was from EK. IMO those PE rads are unbeaten in value and performance in that price category. The blocks are top performers too but as i mentioned before, there are other options if you dont like their look. XSPC make good blocks (although the CPU mounting is a little annoying), Koolance 380i is also a great block. I usually choose EK because i am familiar with their range and their CPU blocks come with mounts for all sockets and you have the option to buy spare tops (for all kinds of EK blocks) if you want to change colour or replace a cracked top, these spares cost about £10 last time i checked. There are also naked mounting plates if you fancy de-lidding and having direct chip contact, these only cost a couple of quid and does not just ensure good contact but prevents you from cracking the chip.
I don't recommend EK because i feel they are superior. IMO pretty much all the entry level gear is roughly the same (apart from the PE radiators which are great) and same could be said for the upper end blocks. I recommend them because the blocks tend to come with everything and spares can be bought for the blocks to replace parts which would put the block out of commission if damaged. The 4.0 pump is the cheapest powerful pump available, the only things worth considering over it, costs a fair chunk more and will likely require a pump top too.