Alad [1] filed a deletion request for arch-package-download [2]: Unlike what the comment suggests, pacman _can_ download packages without root - you just need to pass on the --dbpath option with a user-writeable path.
[1] https://aur.archlinux.org/account/Alad/ [2] https://aur.archlinux.org/pkgbase/arch-package-download/
