The price of tube amps...

They seem so expensive compared to solid state.

Is this because of the actual cost of building them or the fact that theyre considered more "real?"

They seem pretty simple. Probably more simple than a solid state.

Mainly cost of parts. Transformers, parts able to handle higher voltage
and, of course, tubes make tube amps generally more expensive than
solid state amps. Some boutique tube amps are really expensive
because they are hand wired and use components that are NOS or
custom made.

It also has a bit to do with the "mystique" of tube amps.