The existence of cost with bandwidth for the streaming service

Basically, I'm going to launch an application for streaming music, and I'm trying to figure out the cost.

Cloud services such as S3 and RackSpace are expensive. As for scalability ... I assume that the average user listens to music for an hour and allows us to say that our application scales to 100,000 users. This is approximately 90 MB / hour per user bandwidth ... Let me make one more assumption and say that we have an average of 10,000 simultaneous users who broadcast music for 24 hours (90 MB (average / hour) * 10 KB * 24 = 21.6 million MB = 20.5 TB) ... This is crappy bandwidth loading! According to the Rackspace price, it's $ 3,780 USD per day ... Hollywood shit! Moreover, services such as Rdio, Grooveshark, etc., Have about 15 million (licensed) songs ... If I mix it through this, it's 15,000,000 * 3MB (average song) = 43.945GB = $ 4,300 in month.

Thus, at these rates, companies such as Rdio and Grooveshark, etc., do not in any way pay for it.

So my question is simple ... generally, what routes should be followed when creating a streaming service? Being concrete, I would get my vote! (AKA, links to well-established companies offering cheaper CDN services or without interference for a fixed rate)

Thanks duders!

Further)

Application servers will be hosted on Rackspace ... but that doesn’t matter a bit, given the fact that I really need a fast "cdn"