Cardiff City have introduced a new demand based ticketing system for the new season.
Matches will be categorised as Bronze, Silver and Gold with a lower starting price available when the tickets go on sale (this will always be higher than an Ambassador matchday price).
As more tickets for the games are sold the club have the option to increase the prices using the information delivered by the new system. It's similar to how hotels and airlines sell their products.
An explanation of the system can be found here on the official website.