When I asked this company why the unusual cost difference they said they would get back to me. After trying several times to pin someone down, I gave up . Almost always when someone does not receive the desired results from a pure herb or has had a bad reaction, it is not from the herb itself but from the insecticide that was used on it. They can not and try not to wash it off. You may be trying to go natural but are putting toxins or poisons into your system.
Many insecticides are extremely dangerous.
Volatile oils are lost if the herbs is dried too quickly or at too high of temperatures. Mold and Mildew can develop if the herb is dried too slowly or incompletely. Most plants have different varieties. Each variety has slightly different levels of nutrients. The variety which has the higher amount of active ingredient is more potent.