Imo the problem of SSDs is that even super-cheap products easily hit or exceed the sweet spot (which for me is at least 1TB of capacity and 1-2GB/s of read write speed, and lack of judder/slowdown when near capacity).

A ton of affordable SSDs can do this, and after that (well, I'd pay for 2TB but not more), any upgrade is not noticeable for the end user.