Please listen to this guy's suggestion of making the price for both only marginally higher than the price for the Print version alone. One of the quickest ways to kill my interest in in purchasing a book is by expecting someone to pay a non-trivial amount of money for a digital copy after they just purchased a hard copy at full retail.
As far as pricing the ebook alone, I think it should be somewhere around 14.99 to 19.99.
If it helps, I am probably a good example of your target customer. I didn't take my education seriously until I was out of high school for a few years, and now I find myself trying to catch up with all of the stuff I should have learned when I was younger.
If it were a one-off download, it probably wouldn't be. But I quite like the system O'Reilly uses: $5 for an ebook if you own the dead-tree version, because you can download it as many times as you like, in all different formats, and they maintain it with errata updates etc. for life.
The lifetime ability to download the most-current version of a book in any current format is, IMO, worth a few dollars more than a free but unmaintained ebook in what may very easily become a legacy format within a few years.
Good point. Every book should come with a free digital copy, but unfortunately the standard practice seems to be to offer a trivial discount when purchasing both.
The digital copy offers something the physical copy doesn't, e.g. portability. Some people might be willing to pay an incremental sum for this added benefit.
As far as pricing the ebook alone, I think it should be somewhere around 14.99 to 19.99.
If it helps, I am probably a good example of your target customer. I didn't take my education seriously until I was out of high school for a few years, and now I find myself trying to catch up with all of the stuff I should have learned when I was younger.