Archons, IMO are too expensive for low points games. Here are some lists for DE at 500 points.
List #1
Haemonculus, Stinger, Scissorhand 35
20 Warriors, 2x Lances 180
15 Warriors, 2x Lances 180
15 Warriors, 2x Lances 100
Total: 495
List #2:
Haemonculus, Stinger, Scissorhand 35
Haemonculus, Stinger, Scissorhand, Shadowfield 60
5 Warriors, Cannon, Raider 105
5 Warriors, Cannon, Raider 105
Ravager 105
Ravager 105
Total: 510(if your opponent won't let you go over, take out the Shadowfield and add in some upgrades to the Warriors or Ravagers.)
List #3:
Haemonculus, Stinger, Scissorhand, Webway Portal 85
6 Warriors, Cannon, Raider 113
10 Warriors, 2x Lances, 100
Talos, 100
Talos, 100
Total: 498
These can all be modified in many ways, but that's pretty close to how I would run them.
Incubi and Reavers both have no place in low points games, they cost far too much. Also, a warning, Dark Eldar are nothing like Chaos, and suggesting they are offends many players.