Within the LFS QOL instructions, each package has two references for finding the source files for the package—an HTTP link and an FTP link (some packages may only list one of these links). Every effort has been made to ensure that these links are accurate. However, the World Wide Web is in continuous flux. Packages are sometimes moved or updated and the exact URL specified is not always available.
We do not have a solution at the moment if a package download is unavailable besides going to the developer(s) and/or their website.
Obtaining all the source packages all at once is not recommended as you will probably pull in packages you won't want. However, it is certainly a convenient option if you have the disk space to spare. First navigate to the directory you want the downloaded source code and patches to be, then download wget-list. After that, download the packages and patches by doing the following:
wget -N --input-file=wget-list --continue