Where to buy a Possum Box?

Answer 1

You might look at your local agricultural center or you can get them online.
http://www.wildlife-traps.com/possum.html

Or, you can build one:
http://www.nana.asn.au/n2-pbox.htm

Good Luck

Answer 2

What in the world is a possum box? Is it something that you bury them in? I would think that if you were going to bury them that any old shoe box would work. Are you talking about a trap? Most hardware stores will have live traps.