Which using that as an example, I still have my TI 85 my poor/single mother purchased in '92, but I ended up purchasing a TI 84 (ebay) for my middle school daughter this year because that is the calculator she knows how to use because they have them in school. Sure, I could have gotten one of the recent casio's, which is probably a better calculator than the '84, but its the same problem. The teacher shows them how to do stuff on the calculator, and the school's calculator's act as backup if she forgets/etc to bring it to class.
That said, while they are a rip-off, I used the same TI 85 for 8+ years of schooling. Back then that calculator was banned by the college board AFAIK, for testing because it had linear algebra solvers/etc. (apparently its now allowed along with the 89, which makes no sense) Even so, while I was probably the most honest student in many of my college classes there were many times when that calculator had a built in function which would directly solve problems I found on exams. For a few years I had an ongoing joke that engineering school was just 4 years of learning how to use all the built in functionality of my calculator.
It does have the two most recent HP calculators listed, though. That's makes me pretty happy.