I've been having trouble with this for some time. Here is what I finally came up with that seems to work, though I have very limited abilities with piping.
I'm guessing this is a poor way to achieve my goal, are there some simpler ways I could do this that would be more efficient?
$ find /home/data/cam*/* -maxdepth 0 -type d -mtime +30 \
-exec du -sm {} \;| awk '{if ( $1 > 3000 ) print $2}' | xargs rm -rf