Most of the sensors that were hacked there are out of production and have been for several years. You can buy motion activated camera controllers from several sources but they can get rather expensive for your purposes. I'd recommend getting a less expensive battery operated PIR and tapping off the output pin of the opamp. on an 8 pin it is normally pin 7, however on a 16 pin you may have to download a Data sheet for the particular device since my brain has decayed and I can't remember which pin it is.