Sadly, Pinterest seems to have changed their pagination style to be JS-exclusive. Another archiving tool is http://www.downloadmyboard.com/. I suggest you use a service which more inherently supports freedom of user data, such as Dropbox.
gem install pinarchive
Requires curl
pinarchive http://pinterest.com/USER/[BOARD] [OUTPUT_DIR]
Archive a Pinterest board to a local directory. Will not download pins that are already present, so may be invoked repeatedly to keep a copy of a Pinterest account up to date!
If [BOARD] is omitted, all boards in the user's account will be downloaded. New directories will be created for each board under [OUTPUT_DIR], which defaults to the current working directory.