Pico is the latest raspberry pi board and costs £3.60. It is however more of a PIC than a Pi, and is built to control things using C/C++ or stripped down micro Python.
If you purchase the latest issue of the Hackspace magazine you will find a Pico board fixed to the front.
At this point in time I”m not sure how I’ll use it as there is no in-built comms hardware, but it could well be used for robotics as it does have an in-built usb as well as SPI etc. B-)