I buy everything in lossless format and rarely have to look very hard - the few times I had to it turned out to be a vinyl or CD-only release, which wasn't available lossy either. I'm into rather obscure stuff, which may actually help here - I'm not sure but could imagine that it's harder to get lossless audio for the top 40.

Well, here are the stores I use: - Bleep - Boomkat - Qobuz (most iTunes-like with a big selection across all genres, including classic and jazz) - Bandcamp - HDTracks (beware, snake oil! There's no need to go above CD quality in my opinion) - Label / artists stores (yes, many labels or artists sell their music directly without middlemen and in a wider range of formats) - last resort: what.cd or buy the CD and rip it yourself