1. I could have raised my rate at any time, but I didn't until I read the book. If you haven't raised your rates for
seven years, I'm guessing that you've thrown away six figures of lost income. I say this based on an assumption founded on the observation that something like 98% of freelance developers are undercharging for no reason at all. I was. You are. Even just taking inflation into account, you should be charging 20% more now, not to mention an increase in skills, tightening of the developer market, etc.
2. The ebook is something like 90-100 pages and includes a lot more examples, anecdotes, worksheets, and other practical advice than a blog post would. Like you, I've read tons of blog posts about this topic. And like you, I was lazy about raising my rates.
Honestly, I can't believe we're even having this discussion, given our rates and the leverage they imply. If I bill 1000 hours a year (I bill considerably more), every extra dollar in my hourly rate is worth ~$600 annually, after taxes. So if an ebook like this includes a single sentence that changes my thinking or behavior enough that I can justify an extra buck per hour, then it pays for itself 12x over in the first year.
Oh, and I used a $10 off coupon and I wrote the cost of the book off on my taxes, so it really cost me about $25. So it would pay for itself about 24x in the first year if I raised my rates $1. Again, can't even believe we're having this discussion.