I guess my post didn't take, so here is the link again to a cite that breaks down the cost of the $300 million buyback program by Province.
http://www.ssaa.org.au/iladec97.html
$300 million is ONLY the initial cost to buy the guns turned in. Add transporting, handling and destroying the guns, as well as Administrative cost to oversee the massive program and I think $500 million would be quite low.
Canada's buyback program, projected to cost $89 million has cost over $1 Billion dollars and achieved low compliance. Sorry, no supporting documentation for the $Billion cost. It should be common knowledge by now.