co2 in a grow tent?

1st grow. learning as I go. My question is about co2 levels. I'm currently using an exhale co2 bag in a pretty small grow tent, and I haven't turned the fans on yet because it is still in veg. using a desktop fan for air flow. From what I have read about co2 bags, they don't really contribute to the co2 level that much and definately don't go anywhere near 1500ppm. That's alright. I'm just getting started and don't expect too much this time around, but I intend to learn from my errors and get it right in the future.
-speaking of the future- I'm looking into getting either a co2 generator and meter or getting a tank and controller. which one is a better value and investment? how critical is it that your grow tent has a co2 system?

Sugar, yeast, water. probably is 7 bucks total, if its not already lying around the house.

I just leave opened bottles of carbonated spring water in my cab during the day, they love it. Nice n safe too and I water them with the same water.

If you are using a small tent you will probably want to go with a tank and sylinoid ( sp?), A co2 generstor will put out a fair amount of heat and alot of humidity. The cost of making Co2 vs a generator, I ahve heard it is ALOT cheaper using a generator.