[MitziMoto]

Their largest one, which is smaller than a standard piece of paper, starts at $200 and goes up to $270.

For a notebook. With what might be proprietary refills.

What.

[what]

Looks like a standard 6 ring binder and standard paper sizes. You can probably buy the refills from anywhere.

[ukuina]

It's just A6-sized. You can get a soft A6 binder including refills for a tenth that price.