If the data is so valuable that no one should be able to browse it, it should be encrypted.

If you don't want DBA's to be able to select data from the table, don't make them sysadmins. Give DBA's restricted access to the database, and follow some strict security guidelines for the SA account. (Change password regularly, Store it somewhere safe, make sure only a restricted list of people can have access to it, and audit all actions).