I also check the local "big chain sporting goods" store (not Big Five, though, last I looked they only have Coleman). Their MSR cartridges are definitely cheaper than REI. Yes, REI has the dividend, but the gas for the 45 minute drive (25 minutes actual driving and the rest stuck in traffic, lol) takes care of that.
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey