$350 for a device you effectively cannot repair without ruining some part of it is absolutely astonishing. To anybody that says "so what?", if any part of this dies for whatever reason, not only are you almost completely out of your money, there's no way this thing is actually getting repaired by Apple. At best most of the components end up going through a recycler. At worst, that's 5lbs of added landfill.
Speakers are something that NEED to be repaired. It's one of the non-solid state technologies that we haven't found a better alternative for, and are some of the most fragile parts in systems today. These drivers/cones WILL wear out over time and the only thing you're going to be able to do is buy a new unit.