Building your own, with help from someone who had experience with how to do this safely if you need it is much less expensive than buying one from a factory.Yes this sort of thing can be deadly.
A while back I built these 50kg each 805 monoblock monsters that used 900v top cap anodes, I got 50w out of them in the end but I had to use an interstage transformer between the 300B and 805 to get the best sound. https://ibb.co/0yf1fKP
But in the end I stood back and look at what I was doing, and said "YOU WILL DIE ONE DAY" playing around with these things, so I got rid of them and have a longer life for it I’m sure.
Cheers George