Information on the net is sketchy as to whether this is still available; it seems that Snapple started bottling Rain in aluminum cans, which completely screwed up the delicate flavor.
With a little experimentation, you might be able to mock some up in your kitchen, if you have a sodastream.
The ingredients are:
Water, Corn Syrup High Fructose, Citric Acid, Flavoring Natural, Flavors Natural Prickly Pear Cactus, Grapes Juice White, Agave Nectar, Astragalus Extract, Ginseng Extract, Pears Prickly Cactus Puree
It seems to me that you could locate the ingredients at Walmart: citric acid is in the canning section, white grape juice and agave is in grocery, astragalus and ginseng is in pharmacy. If they carry prickly pear, it's in grocery. If not, you'd likely find it at a store that carries Hispanic foods.
It's something to think about, if nothing else.
