I made the kvass recipe in Nourishing Traditions and my kids really liked it. Right now I'm trying to make kombucha tea (just got the culture yesterday so we'll see if it works).

Does he like grape juice? I just made the grape cooler (called "new wine" in the maker's diet"), and it was very good.

I used one litre (quart) of juice, 1 teaspoon of Sea Salt , and 2 Tablespoons of whey. Put all ingredients into a glass bowl, cover loosely and let sit for 3 days. Skim the scum off the top and refrigerate. It's supposed to improve with age, but I liked it so much I don't think it's going to get very old!

Also, the ginger ale recipe in NT is very good.

USXpat

When they say Homemade Whey in the Makers Diet what does that actually mean??

I found this link a wealth of info:
http://www.rejoiceinlife.com/recipes/
Using honey as a Sugar source should make something a child can appreciate since not all the sugars in honey are fermentable. This leaves a nice, sweet-tasting beverage. Apparently.. haven't actually tried myself :-)