Folks, at this time of year, it's easy to get a free yearly supply of juniper berries -- and they will be better than any you'll get at a store...
Upright junipers grow like weeds in the Chicago area. Find the ones with the bluish-green berries, pick a couple, and break them in your hands to test their potency. Good ones will reek (in a good sense) of gin. Now wait for the first hard freeze, and then wait another week or so for the berries to harden off, and at that point you can pick away!
To store for extended periods, you'll need to put them in a dehydrator for 24-48 hours, depending on their size.
Note that once the berries harden off, you'll be competing with the birds to get your supply. And if you pick before the berries harden off, they will have a resiny taste that many people will find unappealing.