Adjusting for the exact size of those plots makes if $3,000,060 per acre of property acquisition, which is $91.85 million for 30 acres of space. That's if Pitt owns NONE of the land, which is somewhat unlikely in Oakland. If Pitt owned, say 20% of the land they wanted to build on, the property acquisition is at $73 million. Maybe it would cost $40 million in site prep (just throwing that number out there based on 60% of the acquisition cost). That means they are paying $113 million to purchase and prepare the space.
The cost to construct a modest stadium appropriate for Pitt's program could be around $150M. So the total is $263 million. It boils down to how much Pitt could secure in donations and their estimated yearly revenue for naming rights, luxury box revenue (which they would now receive 100% of), club and general seating revenue, and other income versus yearly debt service payments, cost of managing the stadium, appreciation costs, etc. They can look at all of these numbers and come up with a donation target to make the project feasible. And just because Pitt collects $100 million does not take away from possible athletics endowment contributions. In fact, it could increase those by providing a better game day atmosphere. Playing at heinz Field only reinforces the attitude that Pitt doesn't need individuals to contribute.