Packaging problem

One of the points I like to make about ecofrugality is that in most cases, the "eco" and the "frugal" are co-aligned, rather than conflicting, goals. For example, let's consider orange juice. The orange juice I grew up with was a frozen concentrate that came in a can, which you mixed with three parts water to get juice. (I can't remember when I learned that you could also extract it from actual oranges.) I'm sure that my mom bought the frozen concentrate because it was cheaper than the stuff in a carton. However, as a budding environmentalist during my teen years, I came to realize that it was "greener" as well, since a 16-ounce frozen can takes less energy to ship than a 64-ounce refrigerated carton and produces less waste to throw away. So, when I entered adulthood, I continued to buy my OJ in the freezer section and felt eco-smug about it.

More recently, however, my eco and frugal sides have come into conflict. In the past year or so, I've spotted a lot of sales on orange juice that have dropped the price of the refrigerated half-gallon cartons below the price of an equivalent volume made from concentrate. At first, it was just an occasional change: we'd stock up on Tropicana or Minute Maid when it happened to be cheap and then go back to the store-brand frozen concentrate when our special purchase ran out. But lately, juice seems to go on sale so often that we always have several cartons of it in the fridge, and before we've finished drinking up what we bought at the last sale, a new one pops up. So without intending it, we've become regular consumers of refrigerated juice, and every time I rinse another one of those cartons out and put it in the trash, I can't help sighing over the waste. (At first I was saving the empty cartons for potting seedlings, but honestly, there's a limit to how many of those things you can use.)

So now I'm starting to ask myself: is it reasonable to keep buying the cheapest juice, or should I choose the frozen stuff because of its eco-benefits? Should I compromise by making the refrigerated juice pay an extra premium to overcome its ecological drawbacks, and if so, how much? With organic products, I have a handy rule of thumb: if the price of the organic product is no more than 1.6 times the price of the conventional equivalent, I'll buy it. But what would be a good equivalent rule for choosing between frozen juice and refrigerated cartons? I'm really not sure how much extra money the ecological benefits should be worth to me. And I can't help suspecting that worrying about it at all means I'm getting a little bit obsessive. Maybe I should just put the whole juice issue into the category of "sweating the small stuff" and try to come up with something more useful to fret about.