It definitely will be their asking price. Ohtani has about $60m in excess value. Chourio has more excess value at about $75m. You would have to add two Frelick's to get to Ohtani valuation. With Frelick and Black you are about $20m short. Frelick, Wiemer and Black would get you to Ohtani's excess value.
I don't see the Brewers matching the value for Ohtani in a trade. I think Ohtani will be on the Dodgers or Yankees. Something like Stone, Busch, De Paula and another piece is close to what it would take to get Ohtani. The Dodgers are probably the favorites for Ohtani at least trade wise as they have a few pitchers the Angels could choose from.