It's interesting to talk about the value of any books or materials. Why do you need them? Are they worth the money? Are you going to use them? Will you learn anything that will make you a better player? These are all good questions to think about before plunking down your money.
I can tell you from the start, that my books are for serious players. People who are thinking of a career in playing Bass. I don't hold your hand through a bunch of basic exercises. These materials are for players who want to take their playing to the next level. People who are serious about the subtleties of playing Bass. Anyone can own a Bass, but it takes years of dedication and practice to really play an instrument. My books assume that you can already play to a certain level. Most players can only get so far on their own and then they start to feel stagnant. Like they are playing the same thing all the time. That's where I come in. I provide the fresh challenging materials that will make you realize that there is much more work to do. I have been a Professor in the Bass Department at Berklee College of Music since 1988. I know the subtleties of playing Bass, and I know how to challenge you and build your skills.
Think about this. A student at Berklee College pays over $200 an hour to study privately with me. You can buy one of my books for around $20. You will probably spend hours on just one page of one of my books. These books took months of my time and effort to put together. That is an outstanding value. You would pay more than $20 for a lesson at a local music store and how do you know how good that teacher really is? He might just be a guitar player who owns a Bass. That's not what you need. You can waste a lot of time practicing when your not being challenged.
Now don't get me wrong. There is no substitute for sitting down and playing one on one. I wish I could hook up with all of you, but that is not possible. That is why I try to offer the next best thing. My books and access to my advice is what I can offer. It's up to you to decide where you want to go with your playing. It's my job to help you get there.