Often the used ones will work just as good. However, though, what's the harm in getting fresh ones each year? Is that too much a financial burden? Anyway, with old books, many will be good - but others could be damaged.
Getting second hand text books is a great way to save money. The higher the grade goes up, the more expensive the textbooks. Except for those workbooks where the actual exercises are done, there is nothing wrong in buying neat secondhand textbooks.
Yeah, but in some cases the state is paying. But then again, taxpayers don't want more expenses either, of course. Anyway, what's the situation in your nation?
In South Africa, textbooks are provided for free in public schools. However, parents are liable for the care and must replace the textbooks if they get damaged by their kids. In private schools, nothing is free. You are responsible for textbooks, stationery and all that.
I am the 3rd in a brood of 4 boys so I have been used to inheriting not only the used textbooks but also the used pants and shirts. That's the tradition here when the family is not wealthy and the children are like stairs with their age. Textbooks cost a lot especially when the school requires more than 5 of them in a school year so we understood the wisdom of our parents.