Essential oils can be purchased from natural food stores, aromatherapy stores, herb stores, mail order catalogs and online stores, according to How Stuff Works. A wide variety of difference in the price of essential oils is caused by factors such as the grade, purity, integrity and type of oil. While some essential oil brands are of higher quality, others are not, and knowing the difference helps with purchasing decisions.
The price of essential oils are based largely on how much of the plant is needed for oil extraction, how difficult the process of extraction is for each individual plant and the cost of the plant, according to How Stuff Works. While fragrant essential oils such as rose oil and jasmine oil necessitate large quantities of the more costly rose petals and jasmine to extract small amounts of oil, others such as peppermint oil, for which the leaves easily grown and picked by machine, are much less expensive.
According to How Stuff Works, the purity, grade and integrity of any type of essential oil depends largely on the brand and price point. Purity is judged by whether the oil is blended with another carrier oil, grade is based on factors such as extraction method and integrity is based on whether the oil comes from one or more species of the plant.