Amazon might be working on a cheap, Echo-only music subscription service

Music subscription services such as Spotify and Apple Music typically cost around 10 bucks a month, but Amazon might soon be offering a service that costs half as much -- if you own its Echo music player.

According to a report by Recode, which cites industry sources, it would cost either $4 or $5 per month, offering unlimited, ad-free music. Typically, that price point is reserved for internet radio services, such as Pandora One, which does not let users choose individual songs to play.

Amazon's cheap new service would offer that, but users would not be able to access it on phones or other devices -- only the Echo.

Launched in late 2014, the Echo is a cylindrical speaker/music player that comes with Amazon's own digital assistant, Alexa. Amazon has not released sales numbers for the echo, but one report claims the company has sold a million devices in the second half of 2015.

Amazon is also working on a standard music service, which would cost $10 per month. Both services could be launched as early as September, though Amazon is still working on the deals with music publishers.

It's not unlike Amazon to tie its hardware and content offerings together into a low-priced package; in fact, even the Echo itself was initially $100 cheaper for Amazon Prime subscribers. But constraining a service to one piece of hardware means your market is mostly limited to that device's owners, and the finer points -- price and possible bundle deals -- could make all the difference here.