Lesa, who owns a small restaurant ...?

Lesa, who owns a small restaurant on the Oregon coast orders three new tables and chairs from Larson’s Furniture Plaza, a local furniture store. She gives the store a check for $1,200, the purchase price of the tables and chairs, and Larson agrees to have the furniture delivered to her restaurant the following week. There is a written sales invoice signed by both parties containing the terms of the agreement. Larson has only one table-and-chair set in stock. When he calls the manufacturer and orders two more sets, he learns the manufacturer has increased the price of the furniture by $200.00 per set. Larson telephones Lesa and informs her of the price increase. Lesa agrees to pay the additional price for the remaining two sets when they are delivered. After the furniture is delivered, however, Lesa refuses to pay the extra amount. She claims that her oral agreement to pay the extra cost is not enforceable because that modification of the contract with Larson was not supported by any new consideration. Is Lesa correct? Why or why not?