My benchmark for the cheap single-board has been the $9 CHIP [1]. As far as I can tell nothing since was able to match that kind of value - 512MB RAM / 4GB MMC / wifi+BT. Hell, it even had a power management IC and a battery connector. I regret I didn't grab more of them before the company went defunct. If anyone knows of a spiritual successor please share.
https://www.kickstarter.com/projects/1598272670/chip-the-wor...