I'll bet if you ask your horse about buying a new amp, he'd say "naaaaaaaay." SS amps may have more "copper" in them than tube amps do, because to run serious power requires serious current; however as the devices are now mostly 50-60V FETs, a bit less current than back when they were mostly 28V or 12V devices. When commonly available 100V FET modules become the norm (not quite there yet), even less copper will be required. Copper is expensive. Also, the heat spreaders and heat sinks required for high-powered SS amps are machined and pretty expensive; both copper and aluminum have increased in price lately and although sinks may be extruded (cheap process), secondary operations like machining the mounting surface very flat have labor cost. Tubes like lots of heat, semiconductors don't. I believe parity has already pretty much been achieved, though -- if you compare "new equipment" prices for products with similar attributes. Tubes have increased in cost faster than the inflation rate, and not many are manufacturing them.