Bad Elephant Music is a great site that offers a lot of independent prog music. There's also Bandcamp.
David's Elliott or 'Wilf' as he's known sometimes runs Bad Elephant and he has knack of taking on some excellent artists. Some of the artists are happy to speak to people on Facebook which is rather nice and oneof my favourites who has a new album appearing soon is the wonderful Simon Godfrey who send to play and do vocals for Tinyfish. He appears on Bad Elephant with some really nice material.
Another band with a new album is Syncage. They come from Italy and I must say, their new album is really impressive.
The other nice thing about Bandcamp and Bad Elephant is that music is available for download in whatever format you choose (including FLAC) for £5 plus tax = £6.
The reason that I like these labels is that they treat the artists much better than commercial companies and they don't rip people off for their albums. You can also preview all of the tracks before buying.