Depends on what you plan on doing with it. Veggie smoothies? You need carrots, zucchini, beets, cucumber. You an add herbs as well (mint, cilantro, etc). After workout meal? I would get a powder protein, oats, peanut butter. You can make nut butters in it (Get nuts) Soups (look up recipes) Ice cream (Frozen bananas are great along with a fruit).
The possibilities are endless. Enjoy your vitamix!