The CO2 Boost buckets can be ordered from a grow shop. They smell foul and IMHO are more expensive than they are worth- sure, startup cost is lower than a tank, but refills will git ya! However, it is 100% safe and can NOT fail in a way that will hurt the humans or plants in your home lol.

I think I paid about $200 total for my entire CO2 injection system- the Hydrofarm regulator comes with timer and tubing too, and then the tank was like $70 with the first fill. If anyone asks, tell the welding supply shop where you buy and fill tanks that it is for the soda gun on your sister's weiner cart.

The last option is a CO2 propane burner that runs on BBQ tanks. I have no experience and therefore no opinion on their function, but a burner may add heat and I try to avoid that in my grow.