Tidal does not post the cost to buy a song or an album on their site

Here's a link to the 'purchasing music' FAQ on Tidal's site:

https://support.tidal.com/hc/en-us/articles/115003672089-Purchasing-Music

It looks like you can indeed buy tracks or albums if you'd like, but that's not really what their service is geared towards, it's primarily a streaming service. 

The 'all sales final, one time download link' part isn't as friendly as iTunes where you can always re-download your purchases even if you somehow manage to delete them, and Apple does allow CD-quality lossless purchases as well.  

Don’t forget veterans pay $11.99 a month for the $19.99 top tier plan.  They will ask for a copy of your DD214 as proof.

One does not "buy" music, only the rights to listen to the music.  You may own the piece of plastic (or vinyl) that is the media for the music, but the rights to the music do not transfer to the owner of the media.

If you only rarely purchase music (a few times a year) and only listen to your music collection, and are satisfied with streaming low res content (for example, YouTube) and/or putting up with commercials (broadcast radio, certain streaming services, etc.), TIDAL will not likely be your thing.  If you buy more than an album a month, demand at least CD quality, and appreciate a certain amount of curation, organizational, and informational content, then TIDAL is a mind-blowingly good deal.  I subscribe to the family plan for $29/month, and I have 4 extremely grateful family members (along with myself) who enjoy TIDAL every day.  I have access to a gargantuan library of CD quality music, which can also be stored on portable devices, for about the cost of a Double Latte every month.  Decision does not require brain.

I still find Tidal to be the best value streaming service available right now.
IMHO it has the easiest interface and best search function, one aspect I really like is when I have searched for my artist as well as listing tracks and albums it will also suggest 5 similar artists. This on its own has got me listening to more new music than anything else combined!

Yes you have to pay $20 for hifi or you can go just $10 for their lower tier service which is still good you just do not get access to the masters mqa titles and if that does not matter then trial at $10 a month. You can always upgrade at anytime and downgrade just as easily too.

Although they do indeed sell tracks it is not really their market target.

Very interesting for those looking at streaming options in the USA right now

https://www.pcmag.com/article2/0,2817,2380776,00.asp