The price range of S/MIME certificates is wide, starting from around €15 up to about €250 per certificate and year. Decisive pricing factors include the provider, class and validation, along with the selected validity period.  Some S/MIME certificates can be purchased with a validity period of up to 36 months. The price per year is often lower for validity periods longer than one year.
On request, SSL resellers can obtain discounts for higher volumes. Please see AutoDNS for a detailed price overview of the individual S/MIME certificates.