Reply #87: I'd have thought working out the cost first would be a better idea

[muriel_volestrangler]

If the concern is the use of limited oil, consider this:

a plastic grocery bag weighs about 0.3 oz (I've just measured this - this reckons 0.2oz. That link is worth reading in this context anyway)
say a round trip to the store in a car is 2 miles - 1/16th of a gallon of fuel, perhaps
1/16th of a gallon is half a pint - maybe 7oz of fuel (it's a bit lighter than water)
So if you use 5 bags per trip, they're still only about a fifth of the oil that you burn to get there.

Granted, the cost may be disposal costs - but 50 cents an ounce seems pretty steep to me.