Complaining over, my problem is that the shaft on the extruder stepper motor has sheared off (the geared one that goes into the gear box)

My question is does anyone know where I can buy a new stepper motor, or even just the shaft/magnet assembly to replace the internals?
I have looked on the makergear website under the motors section and the option that makes most sense to me (Partial Extruder Stepper Motor) isn't available to purchase, so I need to look else where and need it sooner than later as I use the printer for printing parts for a High School FIRST Robotics team and we have a competition next week.