Yes you cannot imagine how well McIntosh sells in comparison to other brands of equal quality or I venture to say better sonics. The reason they are found for sale more frequently than others, as allready said is a function of the numbers sold.
I can tell you that there are probably more Mc s around and working thanalmost any other amp brand. The most freuently offered amps date back to the first generation of SS amps 1967. Those are the Black glass Blue meter designs still used today by MC. The others are often the early tube amps which are collectable and widely admired. However they have been reintroduced in a number of reissues as in the MC275, which continue to draw the audiophile and the Smash Bang Harley Davidson Amps we all at one time aspired to own. They are very reliable, well built and last longer than an army of everyready bunnys. I own a 1973 2505 was a direct descendant of that first SS and still most popular of the initial designs the 2105.
I didn't want to pay a fortune and the 2105 was commanding more than it does now as it delivered over 100wpc and was the best known. The 2505 was a less powerful alternative. To call it low power is misleading, like all good Amps the wattage rating is not very meaningful, it's the power delivered when needed and before it clips. The 2505 is the so called littlest of the black glass blue meter amps that began the SS amps. It's trannies that are much larger than almost any amp so rated.
Some had autoformers and technical improvements like powerguards, with big price tags to match.
The all important "prestigious" nature of being a Mc owner was firmly established by the time Mr. Pass was just begining to think of becoming an amp designer.
It is still considered the best and the quintesenntial American made amp around, if a typical consumer, old enough to know the word Stereo.
They would roll over if they knew they were owned by a Japanese conglomerate which bought the first Japanese multinational that bought MCc a long time ago.
I can't substantiate this but have heard that fairly large sub components aren't built in the U S of A or Japan but a rather large country in Asia.
The sonics of MCs, IMHO are not as nearly as detailed layered as tonally balanced as most Pass amps, so if you do buy a Mc like I did. Have an application beyond the Von Schweickerts in mind. They work well as the motivators for my Klipsch speakers, LaScalas and Heresys. Many acknowledge these as a very odd but very good synergistic pairing.
I any event my advice, which is worth what you paid for it, is hold onto the Pass if you like it/them. If you want to play with the MCs, anyway, try em before commiting a ton of money to buy em or ...
You might like to take your system in a totally new direction and consider a tube amp. The VSAs I have hold their impedance level and up, thus work well with moderate sized tube amps.