Haven't built a computer since I was 14, but got back into it as some of my programming work got too demanding for my laptop. Built this over the month of December, with most of the parts coming from Micro Center as they had a great deal at the time (i7 for 199.99 with 30 off motherboard), though it did result in some of my other parts being a bit overpriced. All the prices include rebates / credit card cash back (1.5% in general 3% for Amazon) taking out, and taxes calculated in (6% where I live). I got the cd-drive and another 16GB of ram free from a friend who upgraded to faster ram and a blueray drive.
I do a lot of programming work, and generally have a few virtual machine open to test things in different versions of Windows using the free https://github.com/xdissent/ievms. My primary operating system is Linux which helped to reduce the overall cost of the build. I do play games on it, but only ones released natively for Steam / Linux (Left 4 Dead 2, all the double fine games, Half Life 2, Metro Last Light) on a 1080p monitor. All of them have ran great on full settings so far.
I decided on a $1000 budget (which I admittedly went a tiny bit over), and this is what I ended up with: