Are you talking about a supplement block or pellets?
Any sort of mouse/rat cube will do as long as its a complete feed and not a supplement ( I found this out yesterdayIm learning LOL ) as some pellets dont have enough nutrition
The pet shop boys warners bay or pmayfield pet stop will have them in stock all the time
Mate your better off getting the rat pellets. $24 bux for 20kgs. That's a complete diet,