The most rich music database.

Hi all,
I'm very demanding music listener and listen mostly what not too many listen and/or nobody has heard or played before. It's sophisticated electronic music, ambient, progressive rock, acid jazz, avantgard, dark rock, neo-classical, new-r&r... another words even King Crimson is too popular for me.
My current passion and devotion: This Mortal Coil, The Orb(William Orbit), Dark.
My objective is to find best combination where
1. number of choices is most important
2. format needs to be no worse than FLAC
3. price per download.

THANKS for your input!