Unfortunately, this is a very competitive rate as all music streaming services are priced about the same. This is not something Spotify can really control due to the complex structure of music licensing and royalties. They have to be paid as well as all the artists they support. The free version of the app is offset by the paid advertising.
It would be nice if it was cheaper - but I find it a better investment than buying everything individually. With streaming, you can continue to support an artist through royalties rather than just a one time download or cd purchase.