Froogle only comes up with one vendor:Hard Drive Power Cable #922-4030 for graphite imac g3.
These guys seem to have the cable in stock as well and they are even cheaper than the two places I posted.AllMac - Your Complete Source for Hard-to-Find Apple Mac Parts
Used these guys once. Can be pricey but you need what you need when you need it, eh? No hassle.
Plus $15 shipping.I think $13 is very reasonable.
Ouch.Plus $15 shipping.