Hey, glad you thought it sounded good. Yeah so basically I build a whole brand new track from listening to the rough recording that the person has - they can send me their ideas and the structure that they would like (V1 v2 Ch etc) and then I get started. Everything is recorded/programmed/played by myself - I sometimes use another friend to help me but its mostly always just me.
The writer can tell me what style they are looking for but there is also an aspect of "handing over" the song for me to put my creativity and ideas into it - obviously I run things past the writer as I go along to make sure they are happy.
I don't overlay the artists original vocals over the finished track because a) thy are normally very bad quality b) the finished structure of the song is different from the rough track that they have previously sent me. I can provide session singers but I have found most people want to sing their own vox once they get the finished track back.
In terms of prices I have been charging around 350quid for the backing tracks with no vocals provided. I think it's pretty reasonable as I try to get the best out of each song that people send me by helping them figure out the best structure, creating the riffs/hooks and then doing all the recording/programming plus mixing and mastering etc. In any particular track I make for people there could be drums, bass, several electric guitar tracks, acoustic guitar, piano, synth, pads, strings - whatever it takes!
Here's another example:
https://soundcloud.com/christianmusicstudio-1/mighty-to-save-backing-track
