[J-Man]

Just an FYI, I would not suggest doing any of the above. Those mass produced props are not designed for continuous use and likely won't hold up for long. Secondly, cutting and crossing or connecting wires to something that wasn't original is asking for trouble unless you're absolutely sure of what you're doing.

 

[J-Man]

If you're handy, a wireless driveway alarm can easily be modified to trigger any prop that has a step pad or try me connection (typically a 3.5mm phono jack). The one that Harbor Freight sells works well for this, it's also sold under different names such as this one from Amazon.
Amazon.com
Modifying it involves opening up the receiver unit and removing the two wires from the speaker. Connect those two wires to a 3.5mm phono jack with a 2 or 3 foot cord. Close up the unit and put fresh batteries in it. Plug the 3.5mm jack into the step pad connection and place the transmitter anywhere you want. When the transmitter senses motion it will trigger the prop.