Hello Chris,
have a look at Farnell :
http://uk.farnell.com/bulgin/px0769-...50?Ntt=978-050
Or even better, ask for their catalogue (3500 pages !!)
You can order even 1 single item, sensibly priced, and (in Belgium) delivered next day withhout cost. Amazing. Have used them a lot for our automatic Lap timing system (
www.chronostiming.be)