The only exceptions to the "Everything's $1" rule are things that are two, three, four, five, and (in the case of seeds) ten for a dollar. It all adds up to a dollar in the end, but you're not getting ripped off.
Why would you pay $1 for a can of pumpkin mix if you can get it at the store for 69 cents?
Also, during Christmas, we sell box sets of Christmas Chinaware for $15 because there are 15 pieces, or $1 per piece.
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Mediocrity at its most average.