raspberry pi 3 - $4,000

aspberry Pi 3 Model B is the earliest model of the third-generation Raspberry Pi. It replaced Raspberry Pi 2 Model B in February 2016. See also Raspberry Pi 3 Model B+, the latest product in the Raspberry Pi 3 range.

Quad Core 1.2GHz Broadcom BCM2837 64bit CPU
1GB RAM
BCM43438 wireless LAN and Bluetooth Low Energy (BLE) on board
100 Base Ethernet
40-pin extended GPIO
4 USB 2 ports
4 Pole stereo output and composite video port
Full size HDMI
CSI camera port for connecting a Raspberry Pi camera
DSI display port for connecting a Raspberry Pi touchscreen display
Micro SD port for loading your operating system and storing data
Upgraded switched Micro USB power source up to 2.5A