We replaced a window in our old house which was broken by DS and a frisbee. The window was approximately 1m x 80cm and the dude recommended safety glass as we have kids and the widow was low so they could possibly fall through it. (Should have seen the massive, sharp shards from the original window - could have done some real damage to a body!) The cost was $180, was about three years ago now. Was cheaper to pay for the window than the excess on our home insurance.