How did you arrive at a valuation for a home - specifically:

Let's say the home they bought together is paid off and worth 500K.

***NOTE: Both parties agree that the home is worth 500K. No need for further discussion on the valuation

He should pay her 250K to vacate, right?

Ok - but he says "you should give me break on this, because if we sold to a stranger we would have to pay taxes and realtor fees and I think that the benefit of selling to me puts the nominal valuation of the home at more like 470"

And then she says "yeah, but I have to go to the time and trouble of finding a new place and then I have to pay for movers and I have set up all the utilities in my name and do all the address changes and it's a real hassle. So I think that should offset the valuation for the home by 20K putting it at more like 490"

Or whatever - just curious how other people did this.