If you live in northern Europe, try out Elfa in Sweden. They carry a tremendous amount of electronic stuff, similar to Maplin UK.
The p.n. for various parts : 75-360-06 TOTX173 Toslink transmitter $10 75-360-14 TORX173 Toslink receiver $10 46-905-33 Square plug $5 55-953-50 Optical wire $4/meterYou also need a 8.2 kOhm resistor for the transmitter. They also have two mini-size transmitter and receiver modules, which don't require any plugs, you just plug the wire in directly. [email protected]