I strongly disagree. Relative to other books, maybe it is on the expensive side. But relative to the value you get from it, I think it is incredibly low.
One way to think about it is in terms of how much you value your time. If you value your time at $25/hr and this book saves you more than 4 hours of time learning UI design, it is worth it.
Another way to think about it is in terms of ROI. As someone in the tech industry I think that having these skills is likely to pay off way more than $99. Not in a legible way -- it's not like anyone will ever say to you "I see you have these UI design skills, here's a $5,000 raise." But I believe that the skills will ultimately shine through and improve your ability to get jobs and make more money.
Also, in practice, if you're in the tech industry, there's probably a good chance that you can get your employer to pay for it.
One way to think about it is in terms of how much you value your time. If you value your time at $25/hr and this book saves you more than 4 hours of time learning UI design, it is worth it.
Another way to think about it is in terms of ROI. As someone in the tech industry I think that having these skills is likely to pay off way more than $99. Not in a legible way -- it's not like anyone will ever say to you "I see you have these UI design skills, here's a $5,000 raise." But I believe that the skills will ultimately shine through and improve your ability to get jobs and make more money.
Also, in practice, if you're in the tech industry, there's probably a good chance that you can get your employer to pay for it.