I just bought a packet of these from Strand Bags, you can get normal one's or deluxe. I got the deluxe one's, where they have a tear off bit with the number on, as opposed to the normal ones where you have to write the numbers down.
They cost me $14.95
Thanks to all on the forum here who have recommended them. I was going to get my bag plastic wrapped, but saw all the info on these tamper tells.
Thanks heaps to you all.