The Fiesta Bowl sold them 12,500 tickets at an average price of $150 per ticket and just assumed that Boise would know that they could sell the tickets for whatever price they want (sell the better seats for more, the worse seats for less, and just price them so that the total cost of the tickets averaged out to $150).

However, when Boise saw the invoice for $150/ticket they assumed that all tickets were to be priced equally and so that's how they went about selling them.

After reading the article and hearing both sides of the story, I've got to think that the Fiesta Bowl wasn't trying to intentionally rip of Boise by undercutting their ticket prices, but instead it just poorly handled the communication to Boise about what price to sell the tickets for.