You've got to be nuts or have money to burn to spend $9K on a cartridge. They all wear out and need replacement!
It used be buying the best shoes or boots was, over time, a savings. They could be rebuilt almost indefinitely. OK not an exact compare but a very important aspect for me is if the cart manufacturer offers realistic-cost repair and rebuild services. The whole trade-in thing seems like a joke imho.
Both lines I work with offer ( even encourage ) maintenance, repair and rebuild services. At VERY reasonable prices. It's a long term relationship. Or at least it can be.