Forgot to mention, I have this barrel trimmer from Penn State too.  There are no replaceable inserts so if you use a lot of acrylic blanks, the Woodpeckers one would be worth the money.  I almost always use wood though and I only turn a handful of pens a year so it's not a big concern for me.

I looked and it doesn't look like Woodpeckers sells the mandrel system any more :(  Didn't see any on Ebay either.  I'll set up a saved search on Ebay though.  IMO, a really good mandrel makes all the difference in the world when it comes to pen turning.

BTW, if you're planning on testing the waters Petey, I'd take pottz up on his offer of barrel trimmers.  They'll work just fine and if you decide pens aren't for you, no money wasted!