You are correct in your statement that I've put in bold print. Your error is in analyzing the "offer and acceptance" part.
The offer wasn't made when they sent out the flyer. The offer is made when the customer offers to buy the product (in this case the tickets) for $155. Until the seller accepts that offer, there is no contract. Their flyer is just an advertisement, or a solicitation to make offers if you will.
It gets a little tricky if you were to pay them online with a credit card and the transaction goes through. However, they probably have somewhere in their "terms" the right to void these electronic transactions.