Guitar amps and stereo amps are very different beasts. To grossly simplify things, wattage has to do with how loudly you can play something before the signal gets distorted. On a stereo amp you do not want distortion, whereas most guitar players are aiming for it. But for both, people tend to prefer how a tube amp clips (distorts) versus how a solid state one does.
New McIntosh equipment is ridiculously expensive, but that's true for anything designed and built in the US to a very high standard today. Not that the used stuff is exactly cheap, but there are much better deals. My amp is a MC2105 which was made from 1967-1977. It is one of their earliest solid state amps, and apparently the circuit is closer to the tube amps of that time, which is seen as a plus. It's conservatively 105 watts per channel and weighs about 60 pounds. It's their earliest amp with the blue power meters which is the look they still have today, but you can get one for $500-$1000 versus $5000 for a MC252, which is their cheapest 2 channel solid amp today (beefier at 250 watts per channel, but still.)