Mark,
Lefthanded_Rock_Thrower - what he said!
eBay is the place to shop. I bought a headset recently there, about $150 cheaper than what I could get in Australia. There are PLENTY available and the whole eBay thing is no dramas at all.
You can get them even cheaper by buying "as new", although you'll get no warranty. To me this is no issue if you're buying quality (ie. DC) - I have used the same DC H10-20 for the last 14 years, and needed only a new mic. cover.
So again for mine,
eBay - hands down.
