Ah, thanks, good to know. I thought solid state power electronics had come down in price more than they apparently did. I guess it's high frequency plus high power that's still expensive. For not so high frequencies (< 1 MHz), mass production for ubiquitous switched-mode power supplies and electric cars has surely brought down the price.

(Side note, modern very high power radio transmitters might also still use some vacuum tube technology - my latest information is that there's a slow transition going on)