So I hopped on over here (after I bought the book) to make this one comment, the price is too low!
Seriously, the amount of value I've already gotten out of this book today well exceeds the $5 buy-in.
I'm not saying to raise it straight to the "typical" $27 e-book level, but I wouldn't have thought twice paying $12 for this. In fact, at $5, you're doing yourself a disservice and signaling a lack of quality.
To add another datapoint, $10-15 is typically fair in my book. Basically for unknown content, the price of a decent lunch or a cheap dinner seems reasonable.
The key to getting a higher price is to "derisk" the investment for people. Demonstrate value with table of content, links to previous blog posts maybe a free chapter of intermediate level (not to basic to make the book seem trivial, but not so advanced as to not be understandable and useful without context).
Books with code in a github repo are worth more to me. The most valuable are those that go as far as to create an immersive environment for learning and experimenting with the concepts. Marijn Haverbeke's Eloquent Javascript book is one of the few that has achieved this with the console/repl that accompanies the book and is integrated with the example code in the text.
I also think $5 is way too cheap for your ebook. OK I understand you don't want to turn a profit. But price is not only for you. It is also for the market. It is viewed by customers/users as a quality element. Low price = Ho! That's just a tiny ebook = Why should I care? (I bought it, looks very interesting)
Seriously, the amount of value I've already gotten out of this book today well exceeds the $5 buy-in.
I'm not saying to raise it straight to the "typical" $27 e-book level, but I wouldn't have thought twice paying $12 for this. In fact, at $5, you're doing yourself a disservice and signaling a lack of quality.