What is Amazon Cloud Drive?
Amazon Cloud Drive is your hard drive in the cloud. Store your music, videos, photos, and documents on Amazon's secure servers. All you need is a web browser to upload, download, and access your files from any computer. Get more details about using Cloud Drive
5 GB of free online storage
Your Cloud Drive comes with 5 GB of free storage—enough space to store up to 1000 songs. This space is yours to use as you like and you will never be charged for it.
Unlimited, secure access from any computer
Use your Amazon Cloud Drive as the go-to location for all your important files. At work, at home, during your commute or while on vacation—you'll always have access to everything you've uploaded to your Cloud Drive through your Amazon account.
Never worry about losing your files again
Store files in your Cloud Drive and never worry about losing them if your computer crashes, or is lost or stolen.
https://www.amazon.com/clouddrive/learnmore
Additionally, you can get a "free" upgrade to 20GB of storage by purchasing an Amazon MP3 album.
http://www.amazon.com/gp/feature.html/?ie=UTF8&docId=1000667531
I don't see a price requirement on the album, so the hunt begins for the cheapest album on Amazon.