As I find castings I love, I would love the option to essentially subscribe or follow a casting so I am alerted when a new version is added so I can wishlist it or not.

Potentially this feature could also be the basis for multiple options in the future. For example if you ever add the option to volunteer location or location spotted, you could be notified of sightings in your area for those specific models. You could see things like most followed and wishlisted cars in your area helping others find the cars if you report sightings. You could even gamify it and give badges for people who report they were successful in their hunt due to your tips.