No, I'm not. In both cases I'm assuming they are owned by the school and giving the costs to provide them for one child through the four years of school.
Schools already have books so the only ones bought are those to replace. Occasionally a new batch may be bought, but not at a rate of every book, every 4 years.
Based on your maths if you consider that each student uses 17 individual books per year, now consider that 2 are scrapped and need to be replace the cost for that year for that students is only 2 * book cost ($80). So $160. Now consider that they attend for 4 years, thats only $640. Not thousands. Even if they are scrapped every 4 years, the cost only becomes $1,280 per student.
So to go paperless from the current system the device and content needs to be less than $640 for the students entire attendance at that school (4 years).
A device like the iPad won't last 4 years in an education system, not including the battery life and software support by Apple.
Great for a private school, but as the education system currently stands. No way.