Thanks, Cindy!
I'm assuming they fill your personal tank? Ohh, and do they make you wait a few days or fill on the spot? I don't mind paying a bit more as long as they fill my personal tank. If I had known that S&S would have stopped then I'd have bought a tank locally and did the trade in thing.
Sorry, I don't know of a place that tests and certifies. Hopefully you'll find a place soon though!
I ended up getting mine filled at AirGas last time. I had to be without co2 for like a week. They were going to charge me a ton (I think like $25-30 or maybe more) but I ended up getting it free (short story: they thought they filled my tank and told my dad it was ready, found out it wasn't filled and he had to wait awhile to pick it up, so they gave it to him free for waiting).
I'm sure I won't get that lucky next time, so I'll probably check out Vulcan.