Think Innovate – Car Electronics

Siren Horn
Is there such thing as a horn or siren may be alone, and connected to an electrical outlet?
For Halloween I need a siren or bell that can connect a motion detector. It must be a separate unit that can plug into a standard outlet.
Couple of places on the Internet http://www.theatrefx.com/store/commerce.cgi?product=police_siren_traffic http://www.smarthomeusa.com/Shop/Security/honeywell/Honeywell-Modules-Acc/Item/HSA600/ [...]