Pirated OS probably, that'd save $100 I guess.
And while it's more cost effective to build one's own, the OP has stated he'd rather not deal with the process. Many people prefer to just be given a working system and not have to deal with potentially DOA parts or warranty issues. It's a nice thing to have the sense of security that if something goes wrong it's not really going to be your problem but whoever put your system together for you.
That being said, back to the system. Going through the configuration on iBuyPower's site and the prices are reasonable enough. Don't really like the mark-up on the video cards or ram but that's to be expected from a company in their industry.
Two questions:
1. Is storage space an issue or could you store your files elsewhere and have this system come with an SSD?
2. Are you fine with swapping a few parts from the pre-built they send you? Basically you buy the base system but swap out certain components like the ram, video card, something relatively easily swapped.
You can not really save money but have back-up parts if you're willing to swap out. Otherwise, I think this build is pretty decent:
http://www.ibuypower.com/Store/Intel_Z77_Core_i5_Configurator/w/120075
Important parts:
CPU: 3570k
Motherboard: Gigabyte GA-Z77-D3H
Ram: random 8 GB set (4GB x 2)
Video Card: AMD Radeon 7850 2GB
PSU: Corsair 750TXV2, could save a decent amount here but I'm not sure what they mean by "standard" PSU or if its worth using. Anyone that's bought systems from iBuyPower, input would be nice.
HDD: a 60GB Intel 520 SSD, also got Windows Home Premium 64 bit for it.