Banana Pi looks the cheapest, so I voted for that.
However, the Raspberry Pi rules! Why does anyone need anything else? For an audio player even the Pi is overpowered and with Volumio and an I2S DAC works perfectly (of course, there’s room for improvement and more features ).
My view is that the cheapest boards should be developed for (as long as they’re powerful enough). Is there anything cheaper than the Pi yet?