what I think
$15 US is really expensive anyway. I am new but what I've found is that the linux communtiy isn't out to make money, just good software. Like what has been said--- you're going to pay $50 US for tech support and a book. I can have someone burn them for me or I can order some sets for (3 cd's) for around $6. It seems that just the nature of the community discourges profit on the software.
I don't know much about the history of Linux/Unix, but do you think that selling the kernal that Linus made would be very ethical? Anyways-- when you pay more than $15 or $20 your paying for a OS consultant.