First, I think Buehrle/Zobrist/Uribe over two seasons will cost around $60M not $100M. And Price is going to cost more than 150M over 7 years. Verlander got 180M over 7 year and Scherzer got 210M over 7 years, though admittedly heavily backloaded. Lester got 155M over 7 years. Price is significantly better than Lester and will be paid accordingly. So once we move to more realistic numbers, I think the case is pretty clear.
Second, I don't view Buehrle as an improvement over the in-house options. I advocate signing for him as a means to create the depth that would allow us to trade a major league ready starting pitcher for a catcher. I'd rather be able to sign a catcher but I don't see one among the free agents that I really like. So I think we'll have to trade for one. I suppose we could trade someone like Peraza for a catcher, but my judgment is that Peraza will turn out to be a bit better than the consensus and would rather hold on to him.
May be the perception is that Price is better than Lester, but stats tell a different story (at least in relation to when Lester signed his deal). Price will be a year younger than Lester when he signs his deal and has a better track record health, but performance-wise Price is certainly not "significantly" better than Lester was when he signed his deal. It's possible Price gets 175+. But I don't see it personally.