And my advice is don't buy one of the prepackaged watercooling setups.
Some of the stuff I find isn't that good and you can get better.
Do a little research into everything before you buy it.
And never buy the coolants completely useless expense.
Distilled water and a Killcoil (Silver strip) is all you'll need.
Also avoid barbs but this is from a personal preference as I see them as very risky and more prone to pop off, go compression fittings.
What case are you rolling, I looked at a setup that could handle a cpu @1.5v + dual 780's and the total figure (I needed another case as well) was roughly $800 AUD so depending on location you could possibly get off for less, best places to try is overclock.net and Linus Tech Tips forum (watercooling board) isn't too bad either. You need to give a large amount of information though for people to be able to help you (intended hardware for the loop, intentions of upgrades, noise tolerance, case, internal or external loop...)
Aside from that I would mostly be echoing FearXI on everything, not a fan of barbs, coolants aren't a great idea (they degrade quickly and add additional maintenance to the loop, the pre-packaged solutions aren't the greatest, D5 pumps are great, research the amount of rad spacing you will need (there is calculation out there for volume of rad = xxxW TDP [The more you over estimate the quieter you can run your fans]).
If you need any help shoot us a list of the hardware you will be using and we might be able to help but you will most likely get more complete help from the other places mentioned.
A bare minimum CPU custom kit with everything necessary is ~$150 (eg. XSPC). A full GPU block is $100. A GPU only block is ~$50 but forgoes VRM and memory cooling.