A few years back Panasonic had a keyboard that only weighed about 30 pounds, yet had a great piano sound and feel. From front to back it was only about 10" deep, which was why it was so light.
At the time I remember feeling that as a digital piano it was far superior in sound and feel to the Kurrzweil.
Drawbacks were it only had a couple of sounds (piano and electric piano, but they both were killer) and very little in the way of physical controls (no pitchbend, etc.). No internal speakers, built in music stand, legs, etc. either.
But it sold new back then for under $1000, and if all you need is a digital piano if you can find a used one it might be hard to beat.
If I stumble across the model number I'll post it.