Are you talking about this device?
Tesla launches new Wall Connector with NEMA 14-50 plug - Electrek
Those seem to command between 300 and 500 around here, but I think the last one I saw was listed at $450. They aren't super common, but at the same time The Gen 1 kit provides similar functionality, but likely with fewer safety features. These don't offer any load sharing features, so not something you can use for many of the larger installs.