In my opinion, the question to buy or not to buy a cd/music is not so easy to answer.
There are a few problems, which can prevent you from buying:
>The following claims are purely subjective, of course!<
Many many great songs from great artists will stay unreachable for you, because you simply don't know, that they exist!
This is (my) main issue.
If you like a song, do you like the whole album?
Probably not! Will you buy the CD just for one or two songs, you like?
There are CDs, that they are so old and so rare, that you cannot buy them anymore, even if you wanted to.
A little example would be the early versions of 'CafÃ© Del Mar' from Energy 52. Especially if you want the original LP-Releases.
Sometimes there are artists, that appear only on compilations and don't release an own album (correct me if I'm wrong)
just a few examples:
Cantoma - Balafia, The Call, Katja, Pandajaro, Early Till Late, ...
Miasma - Serum Switch
Ajax - Story of Life
Carbuncle - Drum & Bossa
Cydonia - Galactic Rebirth
Ohmega - Tribe Panacea
If I like an artist's album and if I have the ability (import orders included), I buy the music!
Again a few examples of cds, which I bought just because I heard about them through the internet or radio/TV:
Aural Float - Freefloat (heard the song 'Zwei G' @ HR-XXL digital radio)
Saafi Brothers - midnight's children (heard the song 'the witness' @ Space-Night)
Der Spyra - Elevator to heaven (heard the song 'last train to bayreuth @ shoutcast)
Der Spyra - my little garden of sounds (heard the song 'seeds' @ shoutcast)
Bobby Hughes Experience - Fusa Riot (heard the song 'Seasons' @ shoutcast)
Tosca - Suzuki (heard the song 'Doris Dub' @ shoutcast)
The Sushi Club - Sushidelic (heard the song 'Niku Jaga' @ HR-XXL)
Gentle People - Soundtracks for living (heard the song 'Journey' @ shoutcast)
Global Communication - 76:14 (heard the song '14:31' @ shoutcast)
De|Phazz - Godsdog (heard the song 'Anchorless' @ guess what? right, shoutcast :))
Energy 52 - CafÃ© Del Mar [Nalin & Kane / Hybrids Time Traveller Rmx] LP (heard the song 'CafÃ© Del Mar - Three 'n One Rmx' @ DF1 radio, Germany's first digital broadcaster, now merged into 'Premiere World')
Since by prefered music genre is more or less away from mainstream, you won't find them out easiliy.