I'm sorta in the same boat as you, just I listen to different genres than you do. like progressive metal, djent, metalcore, deathcore, general rock, as well as some EDM like hardstyle and house and some chill-step. Still basically non-existant on any website to download in flac. So far the best solutions I could find, is either just go full illegal with a rip online, hope the band/artist is on bandcamp (this only really works with unknown bands or artists, since anyone huge and famous doesnt really use it, thankfully a lot of bands I listen to use bandcamp though), or buy the cd and use something like dbpoweramp to rip it into whatever format you want.
Also I reccomend to use a different media player other than itunes, something like foobar 2000 is free and works great after you get past the initial set up. Because something I didnt realize when I first got into all this, was that different media players have a pretty noticeable affect on the sound. Like if you pull up itunes, and foobar to compare back and forth with, you will notice theres a difference in the sound. I prefer foobar because I feel its the most honest version of the song, and just plays the data as directly as possible to your set up. With itunes I know theres some extra internal eq to make it sound "good" according to apple's criteria for good sound, which I am not a fan of. I also tried using winamp for a few weeks, and it honestly makes everything sound terrible. When I compared it, it seemed like winamp was making the sound more muddy, and cloudy, and quiet. out of the three, foobar won for me.