Amazon.com: SparkFun Big Easy Driver Stepper Motor Driver Board for bi-Polar Stepper Motors up to a max 2A/Phase Maximum Motor Drive Voltage of Around 30V Includes on-Board 5V/3.3V Regulation Allegro A4988 Chip :
Stepper Motor Driver Circuit - ElectronicsHub
5 Amp Stepper Motor Driver – 22kg Driver Module with Arduino - Circuit Magic