CDPATH doesn't require the export as it is local to the shell session. Simply setting it will work as you'd want and won't pollute the environment for subshells and scripts.
And zsh users get another advantage here. You can use assign to the cdpath array or the CDPATH colon-delimited string, they are both treated the same internally. The advantage is being able to `cdpath+=...`, much like adding to $PATH with `path+=` or removing from PATH with `path^=`. Check zshbuiltins(1) for how to make your variables work like this, or how to use typeset -U to remove duplicates automatically, or $thousand_other_cool_things.
And zsh users get another advantage here. You can use assign to the cdpath array or the CDPATH colon-delimited string, they are both treated the same internally. The advantage is being able to `cdpath+=...`, much like adding to $PATH with `path+=` or removing from PATH with `path^=`. Check zshbuiltins(1) for how to make your variables work like this, or how to use typeset -U to remove duplicates automatically, or $thousand_other_cool_things.