Hi,
I would like to make a list of the cheapest (sub 10-15$) ARM development boards. Any addition to this list is welcome!
ST Microelectronic
STM32F103C8T6 development board (aka "Blue Pill") - 2$ (Aliexpress)
STM32F030F4P6 development board - 2$ (Aliexpress)
STM32F407VET6 - 10$ (Aliexpress)
STM32F407VGT6 - 10$ (Aliexpress)
STM32F0DISCOVERY - 15$ (Alexpress)
PYBoard MicroPython Python STM32F405 IoT Development Board - 16$ (banggood)
STM32 Nucleo-32 (STM32 F0 F3 L0 L4) - 10.32$ (stmicroelectronic.com, without shipping)
STM32 Nucleo-64 (STM32 F0 F1 F3 F4 L0 L1 L4) - 10.32$ to 15$ (stmicroelectronic.com, without shipping)
STM32 Nucleo-144 (STM32 F2 F3 F4 F7 L4 L4+ H7) - 19$ to 23$ (stmicroelectronic.com, without shipping)
STM32G0316-DISCO - 9$ (stmicroelectronic.com/distributors, without shipping)
Infineon
XMC 2Go (XMC1100 target, XMC4200 debugger) - 6$ (infineon.com, 5$ shipping)
XMC4500 Relax Lite Kit - 12$ (infineon.com, 5$ shipping)
Cypress
CY8CKIT-043 - 4$ (cypress.com, shipping vary) / 8$ (Aliexpress)
CY8CKIT-059 - 10$ (cypress.com, shipping vary) / 20$ (Aliexpress)
Atmel/Microchip
SAMD21G18A development board - 10$ (Aliexpress)
SAM3X8E (Arduino DUE clone) - 14$ (Aliexpress)
SAMD11 CMSIS-DAP - 10$ (tindie.com, shipping vary, from user @ataradov)
ATSAMD10-XMINI - 9$ (microchipdirect.com, without shipping) / 11$ (mouser, without shipping)
Adafruit Trinket M0 - 9$ (adafruit, without shipping) / 9$ (mouser, without shipping)
Adafruit Gemma M0 - 10$ (adafruit, without shipping) / 10$ (mouser, without shipping)
Adafruit ItsyBitsy M0 Express - 12$ (adafruit, without shipping) / 12$ (mouser, without shipping)
Adafruit ItsyBitsy M4 Express - 15$ (adafruit, without shipping) / 15$ (mouser, without shipping)
Adafruit SAMD09 breakout - 5$ (Adafruit, without shipping)
SushiBits M23 Mini Pro - TBD (Tindie, without shipping)
Maxim
MAX32625PICO# - 10$ (maxim.com, 15$ shipping!) / 11.47$ (Mouser)
Freescale (NXP)
Teensy LC - 12$ (pjrc.com, ++shipping)
BBC:MicroBit USB interface - 15$ (mouser, without shipping)
NXP
Olimex LPC-P1114 - 14.50$ (Mouser)
mBuino LPC11U24 - 15$ (mouser, without shipping) [End Of Life?]
MIMXRT1010-EVK - 10.09$ (mouser) 500MHz Cortex-M7 with High Speed USB, audio codec, 6DOF IMU
Texas Instrument
MSP-EXP432P401R - 15$ (Mouser) / 13$ (ti.com, 7$ shipping)
EK-TM4C123GXL - 15$ (Mouser) / 13$ (ti.com, 7$ shipping)
Nuvoton
NuMaker Uno NUC131SD2AE - 10$ (sales on direct.nuvoton.com, 7$ shipping)
M052LAN Module - 6$ (AliExpress)
M054LAN Module - 6$ (AliExpress)
M058LAN Module - 7$ (AliExpress)
M0516LAN Module - 7.5$ (AliExpress)
Nordic
HolyIOT YJ-16009-nRF51822 - 6$ (Aliexpress)
HolyIOT YJ-16048-nRF52832 - 7$ (Aliexpress)
BBC:MicroBit - 15$ (mouser, without shipping)
Dialog Semiconductor
HJ-580LA Wireless Bluetooth BLE DA14580 - 9$ (Aliexpress) / 5$ (Aliexpress, no 32kHz crystal)
Silicon Labs
BGM220 Bluetooth Module Explorer Kit BGM220-EK4314A - 9.99$ (Mouser)