Well, it depends on what his focus is, gaming or editing.
For gaming:
i5 4460 - $180
asrock h97 pro 3 - $80
seasonic s12g 550w 80+ gold - $85
case: any you like for $50
1tb hitachi wd hdd - $55
gtx 970 gigabyte gain ward - $330
8gb ddr3-1600 g.skill ares - $80
Actually this is about $60 over budget, but beastly for playing games. The 970's performance per dollar is incredibly good. Otherwise, wait for the 960 which should be about $100 cheaper to completely match the price range.
For editing however:
h97 pro 3 - $80
xeon e3-1230v3 - $230
1600 g.skill ares 1866 - $170
case of your choice - $50
xfx 550w bronze psu - $55
1 tb hdd - $55
leaves $150 for a gpu. Possibly a 750 ti.