Good point. Too often we indentiry one compound (or perhaps a handful of compounds) in a natural plant and then attempt to substitute that one compound for the natural source (or an extract of the natural source). Nature tends to work synergistically and we often do not understand all of the compounds which are essential elements of one plant that is used to fight cancer or another disease or condition and when we try to combine one or two other supplements of plants that have some of the same compounds the result is not the same. Oleander is a good example.
Even at the higher cost, I would choose the actual wheatgrass.