Here are a few links to check out:
USB GECKO WII (DEVELOPMENT HOMEBREW AND BACKUP TOOL) LIKE SDGECKO Buy Online wii-usbgecko Nintendo Wii Accessories Wholesale and Retail
USB Gecko (Development Tool) - Mod Central Ltd.
GO CYBER SHOP - USB Gecko (Development Tool)
USB Gecko Development Tool Nintendo Wii - Gp2xstore.com
USB Gecko - Homebrew Device/Backup Wii games - $55.00 : OzModChips.com, Australian Supplier of WiiKey, Drivekey, M3, R4DS and CycloDS
As of typing this it seems only the first link (Quantronics.com.au) has them in stock. I can't verify the service of any of these sites as I have never used them.