You can't define "fair" price because that is totally subjective. The market will decide if it is willing to support that price for what the product is. It is incredibly premature to say one way or another if the market will support the price in the long term because of the limited early release, and because most early buyers are either scalpers, people that intend to return them if the don't like them, and people that have to have the latest and greatest no matter the cost.
This will go either one of two ways: it will be like the original Airpods, a resounding success, or like the Homepod a complete flop.
Keep this in mind though: the airpods created a demand for reliable truly wireless earbuds that early adopters quickly were able to demonstrate the value and appeal of to the average consumer, who started buying them en masse. Apple's roughly $8 billion in Airpod sales, if its own business, would be ahead of Foot Locker, Motorola, and AMD on the Fortune 500 according to Forbes. That might happen with Airpods Max, sure, maybe even on a smaller scale. But, the market for large over-ear headphones is significantly smaller. And, like I said, the Airpods like other great Apple products (ipod, ipad, iphone) fulfilled a need people didn't realize they had. What problem do the Airpods Max solve? What need do they fill? Maybe Apple intends them to be just a niche product that will appeal to a small number of people, like the Mac Pro. Again, I don't know the answer to these questions and they are intended to be rhetorical.