So over on this side of the pond (UK) $1.60 wouldn’t buy you a stamp to send a letter, and it certainly wouldn’t get you far on public transport or much of a meal. It’s quite astonishing however what it will buy you in electronics terms. Take for example this Bluetooth BLE Serial UART module!
While I’m not sure what the “Genetical” part of its title means, it looks like a huge amount of technology in a tiny package for very little coin. Based on the RF-Star RS02A1-B system on chip, it should be pretty capable as this is a 32-bit ARM Cortex-M0+ device clocked at 48MHz.
It offers low power consumption while promising decent transmission distance. There is onboard power and RF filtering to hopefully reduce noise and there is a choice of using either the onboard PCB antenna or using the IPEX connector to add your own external antenna.
Supporting the BLE V5.0 stack, the device has 2 UART interfaces as well as I2C. There are also 11 configurable general-purpose IO pins. It’s worth looking over the product page for the frankly astonishing amount of stuff this device has, IR, DMA, Quadrature encoding… the list goes on.
It comes fully assembled with a castellated header; it would be pretty straightforward to integrate this with pin headers or to design custom PCB footprints. It’s a lot of power packed into a tiny package!