Helo,

What kind data encryption are you looking for?

- email? can use PGP - free some/paid some
- files/folder? can save on AES encrypted disk image - free (mac os x builtin)
- whole home folder (working space in the mac) - FileVault - free (mac os x builtin)

just for your info, mac os x builtin security is pretty good, it use 256bit key... military grade...