Bandcamp !! Pay the artist direct (almost^^). Flac and some 24bit same price as Mp3, sometimes very cheap pay as you want.
FlacMeQobuz most of Europe, not for US
or the artist direct if they sell in lossless, many do
Amazon for used cds to rip once - I give most of my cds to my local library now, have too many.
Why would you want to buy Mp3s unless absolutely necessary, especially from itunes?! .. horrible codecs/compression. Can always convert a copy later for your phones.