I think this is a great idea, if you want to put the time into it. First you need to contact the record labels and explain to them what you are building. Work out a good arrangement with them, but only plan on profiting about 10%-15% on your sales at first, for you need to offer a great discount in order to be able to pull in the customers. Next, do not try to get the newest music titles, unless you want to pay big, 2%-5% profit. This is a tough business, but if done right, there is potential.
Already in talks with few artists and record labels .Have spoke to most of them and they seem to be quite interested .They said however we want strict security against illegal downloads and privacy .Some of them even accepted bitcoins as method as payments for their artists !