The 3.5 connector is a pretty standard item for cell phones. I'd go to
Uber
Mart and buy one of their cellphone headsets with a similar plug. You
should be able to get one for $10 or less.

Most cellphones use 2.5mm headset plugs - so make sure to look carefully
before you buy. You might be able to get a 3.5mm 4 conductor cable from
Radio Shack. Digikey sells them for a few dollars:

http://makeashorterlink.com/?V26132F3A\

There probably are also places that sell pre-made adapters to split a 3.5mm
4 conductor cable into more standard mic/headphone jacks. Try a google
search for: 3.5mm "4 cond". You can also buy Dell's $25 headset and take it
apart for the connector.

- Ray