Funny you should bring up the Eastern Sierra AAA map. I worked for the AAA of So.Cal for 32 years and I'm very familiar with that map. It's the best, hands down. My wife still works for the AAA and I'm asking her about your questions right now. According to her you cannot walk into an AAA office and buy one. It's free to members. But some outside businesses do sell it for the price listed on the map front.
Years ago Readers Digest did a study and put out a report on the best values in the U.S.A. #1 was milk, #2 was an AAA membership. They also put out a very good campgound book and a hotel/tour guide.
Maybe I'm a little prejudice in favor of the AAA since they are sending me a monthly retirement check....... No, I'd still give them a thumbs up even if I hadn't worked for them.
Oh and if you want to see an outstanding detailed map for a really out of the way area check out their Guide to the Indian Country, and the Guide to Yosemite is pretty good too. Guide to the Colorado River is pretty detailed and interesting also.