Cheapest place to refill or exchange propane?

[JohnW]

Hey, I use a forced air heater out in my garage and I'm getting tired of getting raped for tank exchange at the local gas station. Where is the cheapest place to get a tank refilled or exchaged?

[DaveH]

That rentall place on Main Ave in Fargo.

[DerekN]

In Moorhead, Silbernagels right on hwy 75 there is $12 to fill an empty tank which is pretty much the cheapest in town I think. Or this side of town anyways.