I'm not sure where you guys live but this is a good place if in NSW:

The Fresh Meat Store - Justfood4dogs.com.au - Fresh Pet Food for your pets!

And like Ashaari - if I have big blocks of frozen and good solid cleaver and a hammer to tap it into the block will break it up. With clean concrete underneath.

It's good to have a cleaver just for this though as the back can be dented.