These seem to be a hot commodity these days and are fetching pretty decent prices. eBay seller putermcgee has currently has five available:
And lastly, the Nintendogs Download/Relay Version.
This seems to one of the more common demos that show up.
This is a kiosk promo found in store displays and during the Halloween holiday people could come into the store and set their Nintendogs game to “Bark Mode” to receive a special gift for their dog!
The seller says that this cart was never used, so the counter on the ‘game’ is still zero. For some reason, I remember another auction stating that the first person to link up received a one time special gift that was only available to the first person. I can’t seem to confirm that however.