The stepper controller postage at $21 seems a bit steep. This mob has free postage
https://m.banggood.com/DM542-Leadshine-2-Phase-Digital-18-48-VDC-Max_-4_2A-Stepper-Motor-Driver-Controller-for-3D-Printer-p-1397322.html?rmmds=search
Very impressive project tho.