I’m can’t answer your questions about the pricing, but can definitely recommend Sibelius. We found it to be very user friendly and intuitive, though the electronic simulation of some of the instruments was not great. My older kid used it during middle school and high school and really liked it.
However, I don’t think the “ultimate” line existed back then; if it did, we didn’t use it. I seem to remember my kid having some frustrations with the amount of memory/space limitations for saving pieces, but only towards the end of high school (when she had built up a fair amount of work). Otherwise, the basic program met her needs. However, she mainly wrote for smaller ensembles, quintets and similar, not full orchestral pieces, which seems to be one of the other bigger differences between the two levels based on a quick look.
It’s somewhat odd that the school uses different software than the teacher; it can be helpful/easier for coursework if the program is the same one the class uses, though I guess not if you’ve found it to be lacking. My kid is in college now, and I don’t know what program she uses (it’s whatever is provided by the college at this point, thankfully) but I can ask if she has any additional input.
