Where abouts in the Northeast are you bcharlton? The BJ's in MA only carry the 8 oz bottles, not the mexican. I can occasionally get it at Stop & Shop for a buck a bottle, but I think I may be wearing out my welcome there having them special order it....................
Same here in south-central PA - BJ's in York only carries 8oz HFCS sweetened Coke. Both Sam's and Costco have the 12oz Mexican version near me.
I also have Reading Draft about an hour north in Reading PA.
http://www.readingdraft.com/Reading_Draft/Sodas.html Been around since 1921, they brew their own root beer, sarsaparilla birch beer (blueberry, white and red), black cherry, grape and a few other flavors. $10 a case in 12oz bottles. I think it's 12 bottles to a case, can't quite recall. Real friendly folks too - I make a trip there a couple times a year to stock up. Makes a nice change of pace from Coke. Different, because they don't 'flash carbonate', my wife thinks it tastes flat but there is carbonation - just much smaller bubbles than Coke/Pepsi. They also sell by the keg and fountain bags. (heh, and no - I don't work there)
Jim