"Cut out the middle man." - Benny Hill
Probably the most under-rated source today is the ubiquitous AudioCD. I see them on the racks at many discount locations and I don't need to tell you how to convert them to MP3s or how to manage them. Cheep.
I also like iTunes and Amazon Audio. The Amazon player runs well on my devices and I can get such over the MP3 for that odd device or for other reason.
It's never been so wide open. Lots of good choices.
I want to start a music library, but I'm not sure where i should buy from. I would like to be able to access this music on any device I have, and may have in the future, through the cloud. Right now I have an android phone and windows laptop, so google play music would work, but if I were to get an iphone or windows phone in the future, I don't think I would still be able to access the music. Where can I buy from that will support almost any device through the cloud?