Amazon
From JRiverWiki
Media Center has an Amazon store built in. It's under Devices in the tree. When you click on Amazon, you'll see the MP3 store. From there, you can try out and purchase MP3 tracks or visit other parts of the store. When you purchase, J. River receives a small per cent of the sale.
MC 15.0.73 introduced the ability to set the store to countries other than the U.S. Note the store settings in the upper right corner of this screenshot:
