Vast Range of Micro Controllers available for electronic controls
PICAXE - simple 8 bit controller 32Mhz 8-20pin around £2 (£15 programmer)
2k byte 3-5V
ARM BASIC - powerful 32 bit 50Mhz 28pin around £8 (£30 programmer)
20k Flash 2k RAM 3.3V
MBED - (see) 32 bit 168MHz ARM: M4 Board £22 (USB cable)
1M Flash 192K RAM
STAMP (PIC16C57C) expensive! from £34
2k byte
Arduino Board 8bit 16MHz from £7 (chip only £5) (programming standard USB cables)
28K Flash 2k5 RAM 1k EEPROM
Raspberry Pi powerful 32bit computer Linux 1GHz from £20
Pic - 8 bit around £3
2k Flash 256bytes RAM 256 bytes EEPROM
NodeMCU ESP8266 Lua WiFi Internet Development Board £3