Whats the Cheapest Co2

I dont want to have any liquids in my grow area but i would like some sorta of Co2 device is there anyway you can use those cartiges that r in like bb guns.Just curious i dont really wanna spent like 50bucks on it if i dont need it, ya no i just figure im runnin my room at 82 average do i really need it i have had not ventilation and everythings been going great i just leave door open.Thanks and appreciate any imput whats so ever.

A friend of mine acutally uses his paintball gun. Walking around his room, "shooting" his plants with little puffs of co2 from the cartridge. I dunno how much it helps, but it's not like it's going to decrease yeild.

You don't need C02....if your ventilation is good then your fine......now adding Co2 will increase your yield but I wouldn't even bother unless your gonna buy the right equipment to utilize it effeciently.....

theres no cheap method i mean im only growing one plant 3.5ft tall for personal, no cheap remedy besides that nasty vinagar n bakin soda or w.e it is.

you could also try gallon jugs of sugar water and yeast. take a peek around the site for some diy co2 ideas.
but like jcdw said about efficiency, if you are going to use it, use it the best you can. if i remember correctly co2 is only supposed to increase yeild up to 25%, which isn't very much if you are only doing a personal or small grow. The increase in yeild probably wouldnt match the raised cost in equipment as quickly as we all would like.

Thanks Kay thats exaxtly wha i need to no....plus rep