The Giant Pet store sell it. For about £6.50ish. I love Megazorb I use mine in the trays.
I get mine from a horse shop (sells horse feed, accessories etc) I use it in a litter tray and as part of the base in the bedroom for 1 of mine as she tends to take to it better than sawdust.
Yes I put newspaper down first, then the megazorb, then straw, then hay.
Yes I put newspaper down first, then the megazorb, then straw, then hay.