Spotted these in the outlet section. Works out pretty cheap with prime delivery as their website is slightly cheaper but charges $10 for delivery.
These are on the smaller side, so if you are after a large knock box look elsewhere. Dimensions as per this harvey norman listing are 11cm x 10cm.
Brown and blue only at this price.
The knock bar is also detachable and easy to clean. Just take it off and rinse it under water.
Nice for the occasional coffee drinker and good price. I had exactly this one before and experienced that coffee went everywhere and not just in the box using this size. I changed to a bigger square one, less mess. I make about 10 coffees per day when not having visitors.