Basically, there's 2 ways to get Coke in glass bottles these days:
Buy the special edition cases (not always available) in the 8 oz. bottles. I've seen these at many Wal*Marts, and even some grocery stores, so check around.
For the REAL, 12 oz. glass bottles we all remember, one does have to buy MEXICAN Coke, which is imported from Mexico, and generally is only sold in areas with a large Hispanic population. For example, in the Greater Washington D.C./Baltimore Metropolitan Area, the easiest place to find it is in Montgomery County, MD. It's stocked at the County's one & only Wal*Mart, and in the Hispanic/International foods aisle in many grocery stores in the area. It's also highly likely to be sold in any Mexican/Latino/Hispanic markets you might encounter in your area.
And as many have already mentioned, it IS the TRUE, "Classic Coke" formula that many of us remember from so long ago, made with REAL SUGAR, not this High Fructose Corn Syrup crap that altered the flavor! Tastes just like Coke USED to taste, back in the Good Ol' Days!