That's very interesting. What do you provide them with - a guide/demo/MIDI track, written music, or just instruct them to improvise along in any way they feel?
For that one I had the drums and keys to start with. Sent it to the bassist with a few examples on YouTube of the kind of thing I was looking for but said just have a crack and see how you get on. Went back and forth a couple of times to say "a bit more like this" etc. Then had the guitarist do the same, followed by the sax, then spent ages rearranging stuff, adding bits of percussion, synth layers etc. The rhythm guitar was supposed to be a more integral part of it but it was badly recorded so ended up getting someone else to play it, but it was a bit much so tacked it onto the end. On other tracks I've written my own bassline but not happy with it so just asked for something similar but more varied etc just had a look and the whole lot set me back £80. The real pros on there charge upwards of a hundred for a short phrase or whatever, but there are plenty of new starters on there who charge a lot less to get their profile up.
