gebruike: Anytime you're trying to sell digital music it's gonna be a hard-sell. The reason being is that there is just sooo much competition out there. I've never ventured into that category, but I wouldn't really bet on it being successful.... Don't let me discourage you though, if you can get that category in front of enough eyes, I'm sure you'd make some profit, not sure it would be big though. ~JJ~
Selling music on Amazon is pretty easy if you choose sub-genres and promote to a niche audience with very specific taste in music. For instance, promoting music to fans of drum and bass is cake since the market is so small and people are willing to buy new tracks all the time. I know this is true because I'm a member of the market and regularly buy dnb tracks to support my favorite producers.
Doing your research is the absolute key to being successful. Trial and Error means you can put a lot of work into a site and it won't perform. Learn about niche research, keyword research and spend a lot of time figuring out what niche to go into before you actually take that first step and buy a domain.
If you're going to get involved with the music category on amazon, I'd suggest following freelancewebaz advice.
I sell music quite well, the commission is insanely low. I get a lot from video streams too, well, a lot at 20 cents each doesn't exactly make serious money though. Physical music is far better. Box Sets that are limited edition and often times priced at $89 - $200+ always get a few clicks and serious collectors will splurge if you write a good review. You have to know what your talking about though, because they can sniff out fakes really easily.
I have a site that sells lesser known electronic dance music mostly in subniches and it does alright. I'm using it not to make money by itself but to boost the commissions on my shed site.