I had some tanks recertified quite awhile ago. Had a hard time finding a place that would do it, and it cost a lot more than 5 bucks.
Exchanging the small tanks is the way to go. Yes you pay a little more, but you are NOT paying a recertify fee.... And if you look at the dates on the full tanks it is easy to get one that has at LEAST 10 years left on it.. Which means that you have avoided paying TWO recertifying fees.
And this can conveinently be done virtually anywhere and faster than doing the recertifying.
So, it's cheaper, faster and easier to just exchange them.
It works for me.
Now the big 30# tanks are more of a challenge. My Costco has them for 65.00 right now. That's a very good price.