Smoke bombs are perhaps one of the best utilized alternative equipment for use in paintball. They are easy to carry, cheap to purchase and easy to use under fire. A well placed smoke will often help you out of a bad situation, or help you gain an advantage over your opponent. Running with the smoke allows you to gain ground on the opposition without him seeing you. I have on more than one occasion walked right up behind the guys shooting at me by using a well placed smoke grenade.
Smoke grenades are no longer sold by paintball outlets. You can find various type of smoke bombs at military surplus stores, Marine supply stores (smoke distress signals at www.boatus.com, www.westmarine.com ) or other variety stores. Costs range from $2 for the small "toys" to $35 or more for professional distress smoke signals.
Check for legality in your area.
Smoke Bombs of any type are not currently available for shipment
Cloud-10 Smoke Bomb
Has a pull pin to ignite the grenade. Burns a white cloud of smoke for about 3 minutes. 10,000cc of smoke

Ultimate Products Smoke Bomb
Has a pull pin to ignite grenade. Burns white smoke for about 7 minutes. 75,000cc of smoke.

Pro Line small smoke bomb
10,000cc of smoke. Available in blue, red, white or yellow smoke. Striker top to ignite the grenade. Burns for about 4 minutes.

Pro Line Large Smoke Bomb
75,000cc of smoke. Available in blue, red, white or yellow smoke. Striker top to ignite grenade. Burns for about 7 minutes.