I understand that Ale Yeah will fill growlers that are not their own, which is a good thing.
I didn't think so, so I checked their website, and you do have to buy their growler. http://www.aleyeahbeer.com/faq/
Ale Yeah just opened a location in Roswell on South Atlanta Street. Just left there after speaking with Eddie, the owner, and he said they will fill 32 or 64 oz. containers brought in from the outside as long as the boiler plate gov't warning about drinking and pregnancy and operating machinery when impaired, etc. is on the container. He said they can paste that warning on your container or you can Google the language, print it out and paste it on yourself.
A perk to having the Ale Yeah growler is that they will swap it with the other size for free. So if you have the 32 oz one and want 64oz of Drafty Kilt, they will just take your 32 and give you the full 64 for no additional charge (on top of the beer). Works the other way too, so if you only want a 32 of the Abita Root Beer, they'll swap your 64 for a 32 and fill the 32.
They only swap the Ale Yeah branded growlers, but they will fill whatever "growler" you have. He said they kinda have to draw the line at milk jugs and soda bottles, but any growler should be good to fill.