Jim Lill has a video testing amp tone:

https://www.youtube.com/watch?v=wcBEOcPtlYk

It's almost entirely EQ and distortion, applied in various orders (the exact signal chain matters, because EQ after distortion sounds different than distortion after EQ). By getting this right you can simulate any tube amp tone with solid state to a high degree of accuracy.

Sure but it’s only been relatively recently that the modeling and solid state stuff has gotten close. And even then, it’s still not quite right. Also, even a good solid state or modeling amp is gonna cost a decent amount. Luckily, we have more choices than ever, and I even have a tube powered preamp that’s absolutely killer paired with an IR cab response loader.

The amp in that photo is a 20 watt solid state practice amp. Those usually aren't very expensive.

Electric guitar tone is ~95% the tone of the speaker, distortion (if applicable), room/mic positioning, and EQ

And a million dollars of studio equipment to record it

Close mic it with a SM57 like your favorite recordings probably did. You don't need any fancy room treatment when close micing. Or just run the direct input through an amp sim and cab impulse response. Unless you're going for a 1950s sound where mechanical speaker distortion actually matters, IRs capture the cab/mic sound very well.

iirc a 50W JCM800 into a Peavey 4x12

The heads aren't so cheap these days, but not particularly hard to come by