Value of placement services for non-members
For industry jobs recruiters are very important for a first time employee seeking contract work.  However for academic jobs I doubt they're of any use.  Like you said there are academic job sites like Higher Ed.  Each discipline also usually has a career website.

If you're looking for postdoc positions your advisor is the best resource because many are given out by word of mouth alone.  Finally each institution is usually required to place job announcements and applications on their HR's web page.  So spend some time going to each University's website.