They're cheap and abundant on the secondhand market, but they certainly aren't large or black. To get your longed-for "big, black display" you might need to re

They're cheap and abundant on the secondhand market, but they certainly aren't large or black. To get your longed-for "big, black display" you might need to rewind the vertical deflection coil on a CRT TV tube; magnetic deflection is going to inherently have more difficulty with high frequencies, but it still routinely reached hundreds of kilohertz in mass-market computer monitors. So, I believe you can get the BBD you are dreaming of. The hardest part is filling the CRT with vacuum, and that's free; people charge to haul away CRTs.