Buying a or related device like the norns is a unique experience because these are boutique, open-source instruments. They don't typically "do anything" out of the box; they are tactile interfaces that rely on external software or scripts to function. Where to Buy New
Because production runs can be limited, the used market is very active: monome midi controller buy
Since monome is open-source, you can find community-built versions: Buying a or related device like the norns