You will need a pump too! Or the water isn't going to circulate the loop. The most popular (I think) are the laing D5s. Alphacool do one (http://www.ebay.co.uk/itm/12V-Alphacool-Laing-D5-Vario-Pump-VPP655-T12-/200770476067?pt=UK_Computing_Water_Cooling&hash=item2ebeda5823
) , as do swiftech (http://compare.ebay.co.uk/like/290511576680?var=lv<yp=AllFixedPriceItemTypes&var=sbar&cbt=y
). From what I have read here on the forums and in reviews, there's a preferance for Alphacool (please correct me if I am wrong). Sometimes people have two pumps in case of error in one of them, but to be honest one is plenty for your loop. You can improve flow rate by getting rid of the standard top and buy a aftermarket one - like the butspower top (http://www.sidewindercomputers.com/lad5wprbimod.html
), which is an absolute beut, but maybe too bling for your setup. You can get other ones too.
If you are really trying to skimp, you could cut costs by simply buying barbs and clamps. Not as pretty as compression fittings but much cheaper. Whatever you do, make sure you buy the right sized barbs/compression fittings and tubing - check the ID and OD of the tubing against the ID and OD of the fittings.
Depending on what you are aiming for - low level noise vs performance (or maybe a balance of both), you should think about the fans you are going to mount on your rads. Some rads work better with fast fans, and others slower. You need to read about that.
Hope that helps somewhat.