Raspberry SC15184 Pi 4 Model B 2019 Quad Core 64 Bit WiFi Bluetooth (2GB) Amazon - $129.90
Raspberry Pi GSM/GPRS/GNSS Bluetooth HAT Expansion Board GPS Module SIM868 Compatible with Raspberry Pi 2B 3B 3B+ 4B Zero Zero W Support Make a Call,Send Messagess,Data Transfer Amazon - $37.55
MakerFocus PWM Servo Motor Driver IIC Module 16 Channel PWM Outputs 12 Bit Resolution I2C Compatible with Raspberry Pi 4 3B+ 3B Zero/Zero W/Zero WH and Jetson Nano Amazon - $17.39