Looks like around the same prices for both, around $15 for 2lbs, but also looks like I’ll have to ensure a tight seal with the fire extinguisher. I’ll look into cheaper regulators and see if I could try and get stuff under $100 for a future project.Not sure how it works in your area. Is it cheaper to refill/buy a fire extinguisher than a gas cylinder? I've seen people using fires extinguishers rigged up to regulators.
Also a lot of Chinese made Co2 regulators and accessories go for cheap on line these days. Not the best but does the job.