https://jlcpcb.com/partdetail/Stmicroelectronics-STM32G431CBU6/C529356 https://jlcpcb.com/partdetail/Stmicroelectronics-STM32G431CB... JLC: $2.1 for qty=1. $1.

https://jlcpcb.com/partdetail/Stmicroelectronics-STM32G431CBU6/C529356 https://jlcpcb.com/partdetail/Stmicroelectronics-STM32G431CB... JLC: $2.1 for qty=1. $1.3 at 1k qty. Loads of stock. It's a low flash and low RAM variant, but sufficient for some purposes. 170Mhz CPU with many onboard periphs.