Nintendo: You can resell Wii Speak
Eurogamer's got a quote from Nintendo UK confirming you can sell on Wii Speak, despite the fact each comes with a unique code.
"Nintendo can confirm that when consumers purchase the Wii Speak accessory, they are provided with a Wii Download Ticket with a unique number. The ticket, which can be redeemed via the Wii Shop Channel, will enable the user to download the Wii Speak Channel free of charge to a single Wii console," said a rep.
"Any consumer who may have misplaced their Wii Download Ticket number for the Wii Speak Channel or require a new number following a Wii exchange may contact their local Nintendo Customer Services department, where they can request a replacement Wii Download Ticket number."
The story originated from this MTV article, which then turned into this bit from Kotaku, but now you need never fret: you will be able to sell your Wii microphone after all.