The
Logitech G500s Mouse is insanely good for like 50-60 bucks.
The
Razer Deathadder is a great alternative if you have bigger hands and like LEDs.
For Keyboard, you're going to want to get a mechanical one. Mechanical keyboards with Cherry MX Blue switches are clicky and tactile (feel sexy as fuck) but can be loud, and if you aren't down for a loud keyboard, Cherry MX Brown switches are a little less clicky and a bit squishier, but are somewhat quiet and less obnoxious.
Out of all the mechanical keyboards,
this is probably the best choice in terms of typing quality and performance, but the
Razer Blackwidow might be better for you if you like lights and gaming customization (macros, etc)
You probably want a good mousepad, since a crappy surface will make any mouse perform like shit.
This mousepad is really good.
Monitors aren't really something you have to be picky about, a 1080p 60Hz monitor of a somewhat well known company is pretty much always a good choice. Here's
one I found for a decent price.
Desk and
chair.
Here's a parts list I've compiled of a PC that is beyond perfect and fits in your budget.
PCPartPicker part list:
http://pcpartpicker.com/p/2tv8I
Price breakdown by merchant:
http://pcpartpicker.com/p/2tv8I/by_merchant/
Benchmarks:
http://pcpartpicker.com/p/2tv8I/benchmarks/
CPU: Intel Core i5-4670K 3.4GHz Quad-Core Processor ($233.99 @ SuperBiiz)
CPU Cooler: Corsair H80i 77.0 CFM Liquid CPU Cooler ($94.99 @ J&R)
Motherboard: ASRock Z87 Extreme4 ATX LGA1150 Motherboard ($134.99 @ Newegg)
Memory: G.Skill Ripjaws Z Series 8GB (4 x 2GB) DDR3-1600 Memory ($84.99 @ Newegg)
Storage: Samsung 840 Series 120GB 2.5" Solid State Disk ($109.99 @ Staples)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ OutletPC)
Video Card: EVGA GeForce GTX 770 2GB Video Card ($349.98 @ SuperBiiz)
Case: Fractal Design Define R4 (Black Pearl) ATX Mid Tower Case ($88.98 @ Newegg)
Power Supply: XFX 750W 80+ Bronze Certified ATX Power Supply ($86.20 @ NCIX US)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($88.98 @ OutletPC)
Total: $1333.07
Total price for everything I've listed together is about 1800-1900. That gives you breathing room for extra cables, a headset, etc.
I'm not really big on gaming headsets, so ask someone else about that :P