I got a used Herman Miller Aeron about 5 years ago for a couple hundred $. Since then I've added a third party headrest. All these years later and it's still in

I got a used Herman Miller Aeron about 5 years ago for a couple hundred $. Since then I've added a third party headrest. All these years later and it's still in great shape. I've seen these actually increase in price on craigslist which is nuts