I have Moritz' book. He says you can buy the cheap malic acid powder at a winemaking supply store. Don't use malic acid capsules because they usually contain other things. You don't want to use Magnesium Malate. You want plain Malic Acid mixed into water.
As to Apple Cider Vinegar, you should look for the good quality, organic kind in the health food store. Moritz says to take 1 T. 4 times per day in water.