I think your still better building it yourself. Ewiz.com has this system builder thing though. The prices aren't that bad for those that can't build it yourself.
http://www.ewiz.com/system_index.php
:begin rant:
Ewiz has not impressed me at all...my boss just gave me a Raidmax case which arrived today from Ewiz damaged...and it took two weeks for delivery...and my boss dosn't want to waste his time trying to get Ewiz to replace it, so he just gave it to me, and will probably order one from the egg.
Ewiz had a problem with the P.O. box instead of an address for the credit card, but made no attempt to call or correct the issue...we had to call and find out why we did not have a tracking number, and had to get on a three way conference call just to verify the card....Security is nice, but this is aproaching ridiculous.
The front cover is cracked, and has 9 broken standoffs, and some idiot hotglued all the bay covers in place.
I do realize that Ewiz is not responsible for damages during shipping, but gluing the drive bay covers? WTF! Couldn't they just put them in a plastic bag and tape it to the inside of the case like all the case screws?
:end rant:
Back on topic: The one caveat that has not been mentioned, is that when you build your own...
You are tech support, so you have to rely on your internet skills to get drivers and software updates.
Edit: One other thing...of all the parts that you can skimp on, the only part that I will never compromise on is the power supply, simply because with a well built supply that has good filtering, even marginal parts like unreliable capacitors will last longer, because when you have good clean power, your components don't have to struggle to work.
If you plan on building computers for money, it helps to have a retail license and with that you can create a merchant account with an etailer like newegg which will significantly reduce your overhead...it helps to have more than one merchant to go to, that way you can say "well so & so has it for xx less" and if not pushed too far, that can reduce the overhead also,