Josh Groban's cover of "O Holy Night" is available for purchase as a single through Pandora.com. The album that features this cover song is available for purchase from JoshGroban.com and eBay.
Pandora provides a link to purchase the song through the iTunes store, and customers must have the iTunes application in order to complete this purchase. JoshGroban.com allows customers to purchase the album with "O Holy Night" on it directly from the website, and it also features a location service to find which local stores sell the album. New and used Josh Groban albums are also available for purchase through eBay.