[joefourier]

If you want an decently peforming SBC that can match the Pi Zero in price, unfortunately you're out of luck. But if you're willing to put in a bit of work, make your own board and suffer most things not working out-of-the-box, you have a wide variety of cheap SoCs and MPUs. E.g. the STM32 MPU line, which has a decent enough ecosystem and plenty of devboards available, and has some chips under $5/unit in bulk.

[MrBuddyCasino]

None of which have wifi, as far as I can see?

[numpad0]

The original ESP8266 ESP-01 was among such devices to add Wi-Fi to host CPU over SPI or UART...

[joefourier]

You need an external module for WiFi, but the standard Linux networking tools and drivers work.