Depends what you use it forRaspberry Pi is good for power saving but actually not cheap at all.
Its not a total package.
We have to buy extra things like SD card and HDD which makes Raspberry Pi costlier.
A music system with your music stored on a server and played through your Hi-Fi via the Raspberry Pi, all controlled by multiple, synchronised Android phones/tablets.
Can you name some headless systems that can do this for cheaper.^ You can do this with any headless system which are cheaper to Pi.