If you are talking about a $4K bike, sure go for the bling.

But if you are looking at building a bike for under $2000, there is sure as $h!t going to be somewhere else you should be putting $100 than going with a $150 headset over a $50 one.

Regarding the value of a $150 headset (such as a King) over a $50 one (like a Cane Creek 40):

Whether a King will last 2, 3, or 4 times as long is impossible to know...

... and in most cases it is also irrelevant.

In the vast majority of cases, a decent $40-$60 HS is never going to be replaced due to wearing out. Seriously, how many times have you heard of a CC 40 wearing out? Or any properly installed and adjusted $50 headset?

I have used countless $40-$60 headsets in many bikes over the past 20 years. I have needed to replace ONE due to wearing out, and it turned out the head tube was in need of facing, so ANY headset would have been toast. I was glad to be out a $40 Cane Creek S2 rather than a (at the time) $130 King.

15 years ago you may have been able to make the argument that the CK would outlast a frame, or that you could use it on your next build, but now headtube standards change so often that you have no idea if you will be able to use it on your next frame.

So AT BEST a CK MIGHT mean you never have to replace the headset on a bike you keep for a very long time.

But how long are we talking about here that you would not get similar results from a headset for 1/3 the cost?

I have 10 years on the CC 40 on my Karate Monkey, 7 years on the CC 40 on my wife's road bike, and an FSA has been on 3 different mtbs over the past 9 years. All of them are still smooth.

In all the bikes I have owned, I cannot think of a single instance where spending the extra $80-$100 on King would not have been money down the toilet.