I really feel for you M-bot. I'm the Maths coordinator at my school and responsible for decisions exactly like this one. I can give you a bit of insight on the use of digital books which we haven't been at all happy with.
For its entire history, our College has had second hand book sales which until about the last 5 years have run successfully and been a great way to ease the burden of new book costs for parents. The publishers haven't liked this, naturally, and have been working towards a scenario where parents are forced to buy brand new text books each year. The way they've done this is by beefing up the "bonus" electronic content which came with the text. Previously on a CD which came attached to the back cover, the electronic content is now only accessible with a code which is only valid for 12 months!
The current scenario that schools are presented with is that we can book list either:
i) brand new text with "fresh" e-content code, or
ii) second hand text book, AND new e-content code
If the parent goes for option 2, whatever money they saved on the book will go on the e-content.
With schools investing heavily in technology, whether from there own funding, or levying parents or simply getting parents to purchase the tech, there is pressure on teachers to use that tech (whether there are to be any genuine learning advantages or not!), consequently forcing the current book list situation.
The publisher we currently use, not that there is much difference between any of them, is Jacaranda. They don't bother to print chapter reviews in their text anymore, it's e-content. So even if parents went for a second hand text and not the e-content, their child is disadvantaged.
It's not just Maths either, it's the 4 core subjects and languages, so far.
The use of calculators in class around Years 7 and 8 is always a bit contentious. While much of the curriculum involves arithmetic (which is to Maths what spelling and grammar are to English) which could be easily done by a practiced adult, and should be easily done by a student, the purpose of any Maths class is to encourage within the student creative ways of applying algorithms, not to demonstrate one pathway to a "correct answer" and reward those students who can mindlessly lemming their way through to that answer. One of those creative means is the appropriate selection and use of technology - particularly the importance of generating within the student an intuition (as much as a cognisant decision) about when technology should and should not be used. This is examined in Year 12 and requires years of exposure to the decision making process.
Our school book lists a Scientific calculator in Year 7, probably the same one - comes in at about $36. But we require the students to keep it until the end of Year 12, where subjects like Chemistry and Physics only permit Scientific Calculators and CAS calculators are not permitted. This way the cost is effectively $6 per year. I think Gok also mentioned that for assessments, iPads would not be permitted, especially for NAPLAN.
Hope this helps