Is there a way to make a device that can see long infrared waves

Is there a way for me to make a device capable of seeing long infrared waves well enough to detect a human at 30 yards away with an air temp of 70 degrees for around 100 usd.

it's called a FLIR "camera".
http://www.flir.com/us/

Check out this link for a modification to a video camera.

Use infrared photo diode.