Recently I was looking for a project that required a network of microcontroler and was looking for the cheapest mcu in around quantity 50. My requirements where pretty modest, I just needed 2 GPIO and 1 PWM ouput.

I ended up ordering the Attiny13A as that was the cheapest option in aliexpress/ebay with freeshipping in small quantities (around USD $0.3 a piece).

I would have loved to find something even cheaper!