Nice script. I do the same kind of search once in a while when the disk that all of our developers share starts to fill up. I'm not that familiar with 'find' or File::Finder so I use this:

   du -a | egrep '^[0-9]{4,}' | sort -nr > ~/du.txt
[download]

The nice thing about it is that it also shows me directories which contain many small files.