To answer the OP's question, Bandcamp allows purchase of individual tracks and the files can be dowloaded in FLAC, as well as other compressed formats. However it seems like most big-name artsts/labels are not available there, so some folks may find the selection lacking. On the downside, Bit depth and sample rate varies by artist/album and is not described in the FLAC download option beforehand. So you get what you get, often it's 16-bit/44.1khz but sometimes higher (one recent purchase was 24-bit/96khz). On the positive side, I think the price remains the same regardless of file type/quality. You can go back into your purchases and re-download a different file type after the initial purchase.
7digital
7digital Canada | High-quality Digital Music Downloads has access to more mainstream artists and also allows individual track purchases. Hi-res FLAC options also vary by artist/album, but at least those options are described in the selection optons. Price increases with bit depth/sample rate, but it's still waaaay more reasonable than HDtracks!
Slightly OT, but I still prefer to have complete ownership of my own music files, independent from any specific service. I purchase from Bandcamp whenever possible, as they try to keep their fees reasonable and pass more on to the artists. It also allows you to pay extra if you want, to further support an artist (I always try to throw in an extra couple of bucks). But I used to tour and record with a few bands and still have many musician friends, so this matters to me. Streaming doesn't pay the average artist a whole lot. I recently started trying Tidal for music exploration, but if I find something I really like, I'll still go and purchase it separately for my own library. That's just my own personal preference though, I'm also trying to atone for my Napster/Limewire youth lol.