The general rule of thumb for fermented veggies is:
Per QUART of veggies:
1 Tbsp salt
4 Tbsp whey
If you don't use whey, they say to double the salt. (I would recommend using the whey, though, since otherwise I think things just get too salty.) Agree with everyone else here -- make whey at home by buying a good quality organic yogurt (grassfed if you can find it, obviously) and straining it into cheesecloth.
The whey will start dripping through pretty quickly, but if you let it sit for a few hours (or even overnight), you'll have lots of whey that will keep in the fridge for several weeks (if not months), and the yogurt that's left will have thickened up into "yocheese" -- basically as thick as cream cheese, and you can use it the same way. Keep it plain, or add your favorite herbs/spices to make a flavored spread you can put on whatever you want. (If you do grain-free "crackers", this would be great on them.)