Laser for an AR pistol

I'm getting ready to build an AR pistol. Bushmaster upper and Spikes lower. I thought I might want a laser aiming system. Any suggestions?

Crimson Trace Laser grips used to make a laser for AR's. If your intrested let me know. I think we still might have one somewhere in the shop :)

Thanks, but I'm just looking at options. I've not considered Crimson Trace though.