Markertek — Check it out!  Markertek sells an enormous line of professional video gear that is not available in any consumer store. Hard-to-find cables and accessories as well as video and production equipment. Doesn't specialize in security camera gear but has a lot of useful accessories for that area. HUGE printed catalog. Very professional service. markertek.com

 Security Cameras Direct — Large selection of a wide variety of security cameras and surveillance gear. Like SuperCircuits, they have a wide variety of low-lux cameras, IR illuminators, mini cameras, micro video cameras, digital video recorders, plus hidden cameras and concealed cameras.  scdlink.com

 SuperCircuits — SuperCircuits sells surveillance equipment and professional security video gear. A huge variety of low-light cameras, infrared (IR) illuminators, CCTV systems, multi-camera DVR systems, covert video, hidden video, cables, wiring, etc. They even have the camera in a baseball cap and camera mounted in eye glasses for covert surveillance! SuperCircuits.com