Nema 23 motors are 56mm square.
the 60mm motors are an oddball so they called them nema 24.
We only sell the 3nm version of the 60mm motor, i tested the higher torque version and found that they performed worse than the 3nm version.
As john rightly says, you cant expect a company to make a bespoke enclosure for near nothing, £600 is not bad, we all need to make a living.