Is it permissible for a student to purchase bones of unknown origin for the purpose of studying from them, knowing that this is not an absolute necessity?

It is impermissible to use a Muslim's cadaver for dissection except in cases of dire necessity or urgent need. It is also impermissible to exceed the scope of this necessity if the educational need can be met through other means. Similarly, it is impermissible to exhume graves and take bones of the deceased for training purposes, or to sell or purchase them.