This was built for an older, non-techie customer who needed a PC to play his favorite game, iRacing. He was on a slim budget, so I had to focus on the games recommended requirements. I started with CPU as I researched the game is CPU and GPU intensive. I got the cheapest i5 I could find. I was happy to find the 4460 on sale.
Next, I was about to get the ATI Radeon R7 260X (was the best available to squeeze the build under $550), but I noticed the Gigabyte GeForce GTX 660 3GB Video Card on sale, and was only $50 after rebate. NOTE: PC Part Picker didn't have the 3GB version listed, so I put the 2GB version in the part list) After bringing this up to the customer, he agreed that his brother has a GTX 660 and loved it, so he was happy to pay the extra.
The case was a cheap deal I got at Micro-Center that I had in stock. Looks great, but kinda flimsy and no USB 3.0 header, but thats ok since the motherboard I used didn't have it anyways.
The motherboard was another part I had in stock, which was a "slick-deal" off Newegg. Nothing crazy, but it worked and was LGA1150... USB 3.0, SATA3, etc.
iRacing isn't very RAM intensive so I got a single 4GB stick which matched the motherboards max speed of 1600 MHz. There is an available slot if he wants to upgrade in the future. The G.Skill Ares was on sale and I liked the blue heat-sink to match the motherboard and fans.
PSU was another Newegg deal that I had lying around. After much research, I found a quality 430W would support the GTX 660 and this build.
After trying to get the customer to upgrade to an SSD, he insisted that a basic, small hard drive would suffice for him and that he really couldn't spend any more. (I had already cheaped out everywhere else to keep him under $600). The drive was a refurb at that, but worked fine :).
The parts were $470 after rebates, and I charged the customer $600 total. I saved an additional $20 from the American Express, Newegg offer.