The easiest way to check the current market value of a given device is to see what they've been selling for on platforms such as eBay.
In this case, you'll want to look for the Tamagotchi Connection V1 (or Tamagotchi Connexion V1, as it was called in some regions). You can safely leave out the "Wiz" part - they're just one of the rights-holders along with Bandai.