We ended up just ordering some grass and veggie powders from http://www.mountainroseherbs.com
... barley grass, wheat grass, alfalfa, spinach powder, oat grass, etc...
You can get them for about $8 per pound, and you can order just 1/4 pounds of each if you want. It is a lot cheaper than the stuff available at the store.
The best commercial ones I have found so far are: Jurassic Greens, Heavenly Greens, Alkalive Green (this one has a YUMMY lemony taste), and Green Kamut. None of these have any Vit C in them, and they are all organic, and pretty reasonable if you shop them around.