There are two reliable sources for alcohol fuel: 1) Denatured alcohol, a mix is ethanol and 10 percent toxic methanol, labelled "lacquer thinner and marine stove fuel", and found in hardware and paint stores and most outfitters in trail towns and REI. Quantities are one quart or one gallon; and 2) automotive fuel line de-icer such as HEET in the yellow 10 ounce bottle, another mix of ethanol with 10 percent methanol. HEET in the red bottle is isopropyl alcohol which will leave a greasy, sooty deposit on your pots. Yellow HEET is found at convenience store/gas stations, gas stations and automotive supply stores.
Other isopropyls such as 90+ percent rubbing alcohol are also readily available in groceries and pharmacies.
If you can't find denatured alcohol or yellow HEET, the isopropyl is a "make do" alternative. It is theoretically a little more efficient, but harder to light, and does not usually get full efficiency from the common backpackers' alcohol burners. One advantage is that you can see its flames in daylight - unlike those of denatured alcohol which has virtually invisible, and therefore dangerous, flames.
So, I guess that's more than 2 sources, but who's counting. Finding fuel on the AT is no problem.