It's more than what you (and I for that matter) think he's worth, but we don't know what City think he's worth, and that's the crucial factor. We will NOT be paying more than we think he's worth though.
It matters hugely for reasons I've explained in previous posts. 5m overspent here is 5m unavailable elsewhere, which could be another transfer, or 10 more jobs in the marketing department).
We go into a negotiation knowing our limits (whatever they may be). If we come out having broken our own limits, we shouldn't be in business.
Do we not just say to Liverpool then this is our max take it or leave it? Why not come out and declare this is what we have done so our name isn't being shit on in the media? We think he is worth x amount this is what we will pay over to you Liverpool. If they accept great if not we move on to other targets when its not too late. After all this we end up paying what Liverpool want where has it got us?