I have the Bas Rutten CDs. They are definitely worth it. They include 2 min rounds with one minute rest and 3 min rounds with one minute rest (around 30 min total of each) in boxing and thai boxing, then there is a workout track that is a real smoker.
What I did (after hearing about others doing it on the Crossfit board) was put the Bas Rutten tracks on mp3 and use a free audio program called Audacity to put some of my own mp3s with the CDs. So now I have Nine Inch Nails or Metallica along with Bas Rutten...I tend to choose tracks with no lyrics. Anyway, if I am alone and just pummeling the heavy bag, I find that after a couple initial rounds then intensity sort of fades. With the Bas Rutten tapes you have to try and keep up with his cadence.
Also, if you do go this route and use headphones, make sure they are ones that will stay in your ear as you're bobbing and weaving.