I built a Heathkit once, it was a stereo FM tuner, a guy had bought and then decided he couldn't do it - so he paid me to assemble and align it for him, I was 16 at the time - and I'd happily have done it for free
But I was incredibly impressed with the quality of the kit, you could see why they were stupidly expensive.
That's what's killed it all off, you could afford to sell an expensive kit back then as commercial equipment was highly expensive, the massive reduction in manufacturing costs means you couldn't possibly sell Heathkit quality kit's as they would cost many times the cost of similar performing factory made equipment.