Gong Li, the general manager of a courier business, saw an advertisement by a car dealer in the daily paper advertising 'Great Wall' automatic sedans at a special low price of $18,000. Gong Li showed her assistant, James, the advertisement and said to James, 'I give you authority to purchase one of these advertised sedans for the business immediately. We need an efficient new sedan for our small delivery jobs which are growing in number, but don't spend anything over this amount.'

James went to the car dealership, and spoke to the dealer, Martin, and explained that he was buying a car for his employer, Gong Li. James showed Martin his business card (which has both his name and the business name - Gong Li & Associates - printed on the card). Martin then explained to James that the Great Wall sedan will be more expensive to run in terms of fuel consumption for intensive use deliveries compared to a more evolved Japanese model also on special at $22,500. Martin convinced him that this would produce substantial savings over the longer term. James phoned Gong Li for instructions but she was not available. James purchased (on the business credit-card) the Japanese sedan and took immediate delivery.

Gong Li upon returning to the office is very upset about the purchase.

Advise James if he is liable for the balance of the money and if so on what grounds? Your answer must refer to relevant agency case law.