Depends on what your needs are.
If, for example, you have a 1280x720, or 1600x900 monitor, it's easier to accomplish than, say, if you're running 1920x1080 or higher resolutions.
Are you looking to play the latest and greatest games? Are you good with averaging 60 frames/sec?
Also, are you buying everything, or do you have any parts you're carrying over from a previous system, such as:
- Windows license (if transferable)
- Mouse
- Keyboard
- Monitor
- (maybe) Power Supply
- Hard drives/SSDs
- Other?