For those people who can't afford a personal trainer, need a refresher course, or just some inspiration, this is a great free resource. Plus, it's not as complicated as many plyometric sources - these are just simple exercises explained well and in a building-block order. I liked it a lot.
I once worked with an eastern-european coach who required simple daily plyometrics for all his students. He did a weekly off-ice class with them, but then expected them to do off-ice by themselves (or with a buddy) every day. I think it helps to get started and check in with a trainer regularly, but if you're a self-starter or can keep a routine, DIY works.