Honestly, I think your best bet is to try and google recipes for making your own.
I have only heard of one, a vegan one I happened across at a health food store, and it was frankly nasty as heck.
If you pick your own protein powder and additives, you can come up with some really awesome protein powder drink mixes. I think you'd be happier with that.
Also, for ideas on what would add protein: amaranth and quinoa are full protein, soy powder is a full protein, too.