If I was building one at the moment here is what I would start with and then start looking more into each part to see what I could swap out to save money/improve performance.
PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-4590 3.3GHz Quad-Core Processor ($243.25 @ shopRBC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($33.05 @ Vuugo)
Motherboard: Asus Z87-A ATX LGA1150 Motherboard ($99.99 @ NCIX)
Memory: G.Skill Ripjaws X Series 16GB (2 x 8GB) DDR3-2133 Memory ($139.99 @ NCIX)
Storage: Kingston SSDNow V300 Series 240GB 2.5" Solid State Drive ($104.98 @ NCIX)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($92.95 @ Vuugo)
Video Card: EVGA GeForce GTX 970 4GB Superclocked ACX 2.0 Video Card ($404.99 @ NCIX)
Case: Thermaltake Commander G41 ATX Mid Tower Case ($70.91 @ DirectCanada)
Power Supply: Corsair RM 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($139.99 @ Memory Express)
Total: $1330.10
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-12 18:03 EDT-0400
Like Andai said, it really depends on what you already have.
Depending on PSU you currently have you might be able to keep it and use it for the new computer. Same goes for the case and HDD which would save about $320 (also OS, monitor etc.). You could then sell your current CPU, mobo, RAM and GPU as separates or as a barebone bundle to someone.