www.7digital.com can also be good and if you happen to be looking for obscure japanese music ototoy.jp is a good resource as long as you dont mind using google translate. but i also often seem to resort to an ebay or amazon cd buy to get my music in lossless.
That said dont rule out just getting in touch with the producers or the label, several years ago i got into some dutch instrumental hip hop, i bought several albums off the site on CD as they didnt offer flac, so one day i just sent an email asking if they would ever consider offering flac as an option.
to cut a long story short i ended up talking to both the guy who runs the label and the artist who now happily send me the original 24bit wav masters whenever he does a new album. (massive respect to both Ryan Goeller of BeatsBroke and Inf (aka Bas Te Braak))
What really kills me though is when youre left tracking down a compilation CD to get a track that was only released on that album (damn you TM Juke! why is Marbles and Drains nowhere else!)