You could take 7 for "free", but you wouldn't be able to activate it. In the same manner, you can get a USB Media Creation Tool for 10 for free, but you still have to pay for the activation code. 10 is a bit better on hardware utilization than 7 was, but I personally still prefer 7. They did an incredible job on win 7, and then decided to go muck it up with 8, 8.1. Overall though, 10 is not a bad OS.
As for the parts list...
PCPartPicker part list:
http://pcpartpicker.com/list/HLNv3F
Price breakdown by merchant: http://pcpartpicker.com/list/HLNv3F/by_merchant/
CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($219.99 @ Newegg)
Motherboard: Gigabyte GA-Z170-HD3P ATX LGA1151 Motherboard ($104.88 @ OutletPC)
Memory: G.Skill Ripjaws V Series 16GB (2 x 8GB) DDR4-2400 Memory ($60.99 @ Newegg)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($61.00 @ Amazon)
Video Card: Gigabyte GeForce GTX 1060 6GB D5 6G Video Card ($254.98 @ Newegg)
Case: Corsair 200R ATX Mid Tower Case ($44.99 @ Newegg)
Power Supply: Rosewill 600W 80+ Bronze Certified Semi-Modular ATX Power Supply ($49.99 @ Newegg)
Operating System: Microsoft Windows 10 Home OEM 64-bit ($88.88 @ OutletPC)
Monitor: LG 25UM56-P 25.0" 60Hz Monitor ($150.98 @ Newegg)
Headphones: Kingston HyperX Cloud II 7.1 Channel Headset ($99.99 @ B&H)
Total: $1136.67
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-08-28 01:00 EDT-0400
Saves you about $60. I'm assuming you didn't put a CPU cooler on the 4690k because you already have one, thus I didn't add one to that.
Personally, if you're very tight on your budget, scrap the ultrawide for a normal $100 1080p monitor (as that's what the 1060 is, it's a 1920*1080p card) and use that $50 elsewhere to improve the rest of the hardware. But if you're set on the ultrawide, that's understandable.