Tenergy via Amazon offers its Tenergy Odev Tomo 2-in-1 Transformable DIY Programmable Robot Kit for $99.99. Coupon code "DNS61297" cuts that to $79.99. With free shipping, that's $20 off and the lowest price we could find. This STEM kit can be built as a tricycle or dicycle and features Bluetooth 4.0, an ATmega2560 microcontroller, ultrasonic sensor, tracking sensor, accelerometer, gyroscope, buzzer, and RGB light. It comes with two free apps, one that controls the robot and one that teaches graphical programming. Six AA batteries are required, not included.