No it was my mistake, I read 'based on' as 'equal to', which was a bit daft. I agree that you need to weigh the cost of relegation in your decisions (at least Palace should), but it's different with us as I assume we'll spend up to the limit of FFP anyway, so the question is not how much to...
I may have misread your post. I read it to mean that you work out what it would cost if you went down, and pay them that - but that's not what you meant, is it?