Dealmac: SendStation’s PocketDock for third-generation iPods is back in stock at MegaMacs.com for $16.99 plus around $8 shipping.
We still haven’t found a cheaper price elsewhere.
(MacMall charges the same but adds an inexplicable $24 or more for shipping.) The PocketDock converts the iPod’s docking port into a 6-pin FireWire port.