I find it in our local grocery stores (Dillons, Kroger, Bakers) or even Wal Mart in a gallon jug. This is the basic, distilled kind, that I use for thrush, etc., as the main part of knocking out thrush is the pH, and that doesn't change with distilled varitey.
If you want it for oral use (arthritis, joint supplement, feed thru fly repellant) I would recommend the kind that has the "mother" in it (the best part of the ACV that is removed when it's distilled, and you should look at the health food sections or specialty stores. This kind is a bit more expensive, but worth it if you aren't just spraying on feet.