Adafruit VS1053 Codec + MicroSD Breakout - MP3/WAV/MIDI/OGG Play + Record - v4

Yes, the Sparkfun board would definitely be easier!

But to get started with the Adafruit one, use the first example on the File IO page linked above:

// Wire up up MOSI, MISO, SCK and CS pins (along with 3.3v and GND)
SPI1.setup({mosi:B5, miso:B4, sck:B3});
E.connectSDCard(SPI1, B6 /*CS*/);
// see what's on the device
console.log(require("fs").readdirSync())­;

(and try wiring the SD card as shown above)

For the Sparkfun board their code is a good start: https://github.com/sparkfun/Audio-Sound_­Breakout-WTV020SD/blob/V_1.0/firmware/Au­dio-Sound_Breakout/AudioModule.ino

Just replace sendCommand with something like:

function sendCommand(command) {
  digitalWrite(DCLK, 0);
  setTimeout(function() {
    for (var i = 0; i < 16; i++) {
      digitalWrite(DCLK, 0);
      digitalWrite(DOUT, (command & 0x8000) != 0);
      digitalWrite(DCLK, 1);
      command = command<<1;
    }
  },2);
}

Also, you know that Espruino can do sounds itself? http://www.espruino.com/Waveform

It may not be significantly worse quality than the Sparkfun board :)