i can't make any specific recommendations, but have you seen this thread yet? http://club.cdfreaks.com/showthread.php?t=144774
once you do find a site that you think you'd like to go with, I suggest you compare it against a lot of the points made in the link that I posted. It's a very good reseource for making sure a source is legitimate!
also, you said itunes doesn't carry what you're looking for. what exactly are you looking for? there may be posters with similar tastes that can recommend a site.