That's understood, was considering a esp board. I don't want to get something that either dosen't work or is to expensive. So a link to a compatible board from a chinese site be useful, im prepared to wait for delivery
You will need 1 1k ohm resistor. 1 npn transistor, 1 usb pen drive, and a wemos d1 mini - total price is less than £5.
Wemos d1 mini is an esp8266 board and hosts the web access point, once the JB payload is sent - one of the pins connected to the pen drive is set high and then set low (same as plugging in and unplugging the usb drive), then goldhen is automatically sent.