I recommend...
go to the Dell site, or any branded site that allows you to customize your own.
You may not like the brand but you will learn a lot about what is available in high performance boxes and a general idea of what they will cost.
For example:
http://www.dell.com/us/p/xps-27-2720-aio/pd?oc=fdcwlp1397&model_id=xps-27-2720-aio
4th Generation Intel® Core™ i7 Processor
Windows 8.1
16GB Memory
2TB Hard Drive + 32GB Solid State Drive
Touch EnabledTouch Enabled
$2500 and up