Black truffles are expensive because of their rarity. They grow only for six to nine months out of the year. To find wild truffles, hunters typically employ trained dogs who can help locate their scent. Truffles have a short shelf life, so they must be shipped and sold or frozen in a very small window of time to retain their freshness and flavor. Many farmers try to cultivate truffles unsuccessfully, because truffles require very specific conditions to grow. They thrive better in the wild and require a hunt to harvest. Though black truffles are pricier than other mushrooms, they're among the most affordable truffles on the market. White truffles are significantly more expensive.