I was checking over the auction pages on eBay, and found these interesting sirens manufactured by Lion King:
http://cgi.ebay.com/ELECTRIC-SINGLE-TON ... dZViewItem
http://cgi.ebay.com/ELECTRIC-SINGLE-TON ... dZViewItem
http://cgi.ebay.com/ELECTRIC-DUAL-TONE- ... dZViewItem
Out of all of these units, I would pick the dual-tone version, as its better at attracting the attention of the residents in any area. I wonder if the Chinese feel there is a rather strong market for their sirens in North America?