looking for single element passive infrared sensor (PIR)

Hi. Can you give me manufacturer names of single element passive infrared sensors and where I should look to buy them? When I look through online electronic parts stores, all I see are dual element or quad element sensors. I realize that the higher element sensors are better for motion detection, but I'm stubborn and want a single element.

If single element sensors aren't made, is there something equivalent, maybe an infrared temperature sensor, that's cheap (under $2)? I need a response time to change in temperature of 0.5 seconds or less, but something under 0.01 seconds would be ideal.

Thanks for your time!