Rolleiflex SL66: 1.92 kg (4.25 lbs.)
This is an awesome camera with interchangeable backs, finders and lenses. The lenses are still rather expensive, and most cameras should be serviced.
You can reverse the standard f/2.8 80mm Planar for close-up work.
There is a special bracket that makes the camera very easy to handle, but like many heavy cameras, a tripod is a good accessory.
This camera probably is way out of your budget unless you chance upon a great deal, which happens from time to time.