I used to download http://www.bzip.org/1.0.6/bzip2-1.0.6.tar.gz
But now http://www.bzip.org/ does not exists anymore.
The source tarball is now at sourceforge.net .
The linux from scratch project also keeps a copy at http://anduin.linuxfromscratch.org/LFS/bzip2-1.0.6.tar.gz