3.5mm audio input connector - $1.60
(http://www.jaycar.com.au/productView...=&SUBCATID=373)

OPTION 1: pre-made computer CDROM analog audio cable - $5.65
(http://www.techbuy.com.au/p/13293/CA...ch/RC-5041.asp)

OPTION 2: standard electric wire - no more than a few bucks; crimping lugs - $2.40
(http://www.jaycar.com.au/productView...=&SUBCATID=601)

Note that I went with option 1 as I had that already, and I'm not 100% sure if the crimping lugs quoted above are the right ones, though I imagine they are fairly standard.

You'll also need a standard 3.5mm male-to-male audio cable to connect the socket to your music device too, plus you'll need a soldering iron to solder the wire to the socket.

Sam