Well...no body really makes dedicated weaponlights to the extent that SF does. Streamlight and Insight Technology make pistol lights, which can be easily adapted to a rifle. Any 1" or similiarly sized light can be attached to a rifle, which is essentially the only other option. Elzetta is the only company that I would trust outside of the weaponlights manufacturers. Oh, and phantom light. You can use a MIC X-fire light, but, which is fine for airsoft, but I wouldn't put anythin like that on a "business" weapon.
Are you trying to keep the price down, or are you just curious? If you're trying to keep the price down, a Surefire G2 w/ LED can be had for about $45-$50. Oh, and SF are recommended 9 out of 10 times for a reason.
Hope this helps a little, and Welcome to CPF!