I tried looking into it. Not very deep, mind you and I just scratched the surface of it.
A bit of background first, though: I am in a predominantly Christian country which acknowledges the existence of dark entities however doesnt really provide information on how to get in touch with one, etc.
So i had to look into it myself. This is made more complex it's not as easy to typing into google how to get in touch with a demon. In my experience the first page of results were bible verses and the need to fight demons, why they are bad, etc etc etc...
Apparently finding the correct one (entity) is difficult as they seem to work like a bureaucracy, there's different layers, etc.
Also a lot of waiting, meditating, etc and reading. Oh the reading. I started with the Lesser Keys of Solomon.
Some people claim to have been able to contact them and successfully entered in a sort of relationship? i guess with them, but I digress.
The thing is, based on traditional Christian beliefs, one will get sent to hell anyway if one commits CTB. so there's really no incentive there to have you offer up something that they'll receive anyway.
Anyhow, I've come to the conclusion that the soul isn't as valuable as what I was taught (at least mine isnt).
It's hard enough to accept that the entity i thought of (God) didnt answer my prayers, it's actually very sad and pathetic that even demons dont see the value of my soul.
But that's my experience of it, maybe yours will be different.