Okay, here is a little deal at Canadian Tire that seems to be somewhat of a secret. This means you have to know about it to get it. In other words, they don't advertise it.
CT has a propane tank swap system in place where you bring in your propane tank empty and they give you a filled one in exchange for $19.99. Its a convenience thing. You pay extra to not stand around at the filler station. The key to the swap program is you have to turn in one of the tanks that "came" from the swap system. They have a easily removable plastic label on the tanks to identify them. Many stores other than CT are part of the same swap system.
This is not the secret.
Here is the the secret. If you own one of the "old" regular sized BBQ propane tanks (the ones that ONLY have the "female threaded nozzle" on the tank) that was "NOT" part of the swap system; then CT will take it from you and give you back a newer pre-filled tank for $19.99. You get to keep the newer tank, take the plastic label off and get it refilled anywhere you want.
Now notice that I keep saying "newer" tanks. The tanks in the swap system are all pre-filled and most are recertified older tanks. You can see the date it was made on the handle.
When they go to give you your replacement tank, insist on checking the date on the handle. A number of the tanks have "made in" dates in the last couple of years and most are outdated recertified tanks. Being good RFDers that you are, you will go get your next refill at the cheapest possible price somewhere other than the swap system at CT. So don't let them give you a tank more than say..... 5 years old. I managed to get one made in OCT 2005.
I only discovered this deal because I took my "old" tank in for a refill to the CT gas station and was told sorry - as of April 1st, 2006, they will no longer fill the "old female threaded only tanks". The boss on the counter told me I had to go to the store and buy a new tank for about $35 then get it filled. But the guy who was certified to do the actual propane filling told me about a secret exchange deal. The boss gave him a real dirty look. I was told to go to the CT service counter and ask about the deal. The first two women at the counter did not know about it until a third women pulled out a binder from under the counter with all the details. After much reading, they said okay. It was news to them. They will insist on seeing the old tank to confirm the female only threads.
BTW, You don't bring the tank into the store. They come outside to see it.
i saw this on another deals site. Havent tried it yet though