I get my cylinders recertified at a propane distributor for $5 each, good for 5 years. A new 6 lb cylinder would have cost about $40 or more plus shipping. New ones aren't available locally any way. Got the 6 lb and 2 20 lb recertified for $15. Will need to get 30 lb cylinders recertified soon.
It only took about 25 to 30 minutes. They did a visual inspection of each, etched the collars of the cylinders, entered each cylinder with my name and address into their inspection book and refilled them with propane.