I really like the content of the post, but disagree with its title. I believe a better title would have been:

"Great things are often free or cheap".

Some examples for better things for that list have been mentioned by other comments. But there is a deeper reason I think the title is quite problematic:

Looking for "the best" seems to me a losing strategy when it comes to quality of life. There is (almost) always something or somewhere else that is better but out of your reach for several reasons (money, distance, time, etc.). If you look for that your experience will be contrasted with a hypothetically even better one, devaluing your own experience.

So, I believe we should not look for "the best", but we definitely should look for "great", for experiences that truly enrich our life and, as you rightfully pointed out, in many cases are cheap and easily accessible if we only start looking for them.

Note that everything on your list has zero or near zero replication cost. A lot of essentials, tangible and intangible, are not like that. Food, companionship, living accommodations, etc. I don't know how far one can get on easy-clone stuff.

Importantly, almost all of your examples are only true very recently. With the exception of nature and comedy, all of these require the internet to get access to. Many of them require comparatively recent developments on the internet.

To contribute to the above: note that there are better versions of the items on your list, but they cost logarithmically more money for relative to the improvements.

Music: meeting a famous bandmember in person is even better than playing them on spotify

Art: Having the actual, tangible piece in your dwelling is still better than looking at it on a monitor (though the game is narrowing)

Writings: There still is a market for commercial fiction that is at least better edited than the typical free fanfic.

Software: Custom software specific to your application is still better than the free stuff.  (well, usually, if you don't get ripped off.  Amazon's internal software is obviously better than anything a similar business can get, but it's exotically expensive)

Education: This is horrifically untrue.  The issue is the general facts are free but the specific high value knowledge very often requires an opportunity cost that can be terribly expensive, and the credentials are expensive.  I can read all day articles online, but a high reputation university to prove I know it to potential employers runs from $8k (OMSCS) to several hundred k (masters at a private school).  

  And as it turns out, the education system is just the start.  The really valuable knowledge comes from specific practical experience that comes at a cost.  A good surgeon has made some mistakes in training on real living humans.  A good aerospace engineer has been part of building several real rockets or airplanes.  A good embedded engineer has actually built a high performance system and gotten it to work.  They used to say a good general in ww1 came at the cost of losing thousands of men.  And so on.

Note that this is a place where neural implants or AI or life extension would help immensely because you wouldn't, as a civilization, have to pay these costs over and over with each new short-lived human.

Nature: the thing is, the really great nature is far away and, well, way more awesome.  The woods of backwoods kentucky are pretty but Yellowstone or islands in the pacific or new zealand, etc, are an entirely different level.

Sports: a general instance of the music case

Movies, live standup comedy: a general instance of the music case

Philosophy: I don't know how quantify 'goodness' here.  

I don't think there are any important caveats, and I also wouldn't expect there to be. The reason I wouldn't is that if the best things in life weren't cheap, it would mean that the best things in life are the things that require lots of highly skilled labour that can't be amortised across a large number of people.

When things are expensive and highly desired, market forces incentivise people to put a lot of effort into making those things less expensive, so the only things that tend to remain that way are:

A) Things where there are hard constraints on how much effort needs to be put into creating them. 

B) Things that derive a large part of their perceived value from being produced in a way that requires lots of bespoke highly skilled labour.

Things that are B are not the best things in life almost by definition, and so few tangible products in the modern world are A (as opposed to say, human relationships) that they are unlikely to coincide with the best things in life.