Yes, it is expensive that it's just plastic with a magnet, the contacts of the charging socket on the Z1 Compact and the Micro-USB connector.
It is not supplied power adapter.
But, it just works well because it's a Sony original accessories.
There are provided two adapters for charging station: 1x normal to the naked Z1 Compact and 1x slightly wider protected in Bumper Z1 Compact.
The phone fits nicely into the charging station and the magnet keeps the phone safe. If you want to take the phone out again, you have either the cradle hold, because it is very easy or the Z1 Compact hebelen out / turn desedimentation the longitudinal axis.