well: arduino [1]: 1.38$ nrf [2]: 0.55$ oled [3]: 2.33$ ------------------ total: 4.26$ like you said the passive components are pretty cheap, and

well: arduino [1]: 1.38$ nrf [2]: 0.55$ oled [3]: 2.33$ ------------------ total: 4.26$ like you said the passive components are pretty cheap, and you stay under 5$. [1] https://www.aliexpress.com/item/EYEWINK-1pcs-lot-ATMEGA328P-Pro-Mini-328-Mini-ATMEGA328-5V-16MHz-for-Arduino-5V-16M/32810156549.html https://www.aliexpress.com/item/EYEWINK-1pcs-lot-ATMEGA328P-... [2] https://www.aliexpress.com/item/LCD-Board-T420XW01-V2-06A39-1A-42WL68C-Logic-board-New-In-stock-In-stock-Best-price/583655445.html https://www.aliexpress.com/item/LCD-Board-T420XW01-V2-06A39-... [3] https://www.aliexpress.com/item/Free-Shipping-Blue-0-96-inch-128X64-OLED-Display-Module-For-arduino-IIC-SPI-Communicate/32681033995.html https://www.aliexpress.com/item/Free-Shipping-Blue-0-96-inch...