Bleep offers FLAC (even 24 bit WAV).
It's mostly alternative and electronica stuff though. It was founded by Warp records (Aphex Twin, Autreche, Boards of Canada, etc) but it now sells stuff for other labels as well.
Bandcamp has no cap on redownloading my library, and a decent mobile app for the stuff I don't keep stored on my devices.
Bandcamp isn't a perfect platform (they finally added a volume slider after a decade+), but they were a great solution to buying and releasing music for me since the birth of Bandcamp.
I've got multiple sources of audio coming from the browser since it has taken the place of so many applications. Generally I'd expect sites that sell/stream music to have a simple volume slider.