Wally has been saving every penny to buy himself a fishing boat when he turns eighteen. First, he selected the model boat he wanted, and then, over the past five years, has managed to save $10,000, price of the boat, from working at summer and after-school jobs. When Wally arrives at the boat dealership on his eighteenth birthday, he is disappointed to learn that the same boat now costs $11,200. The most likely reason for the price increase is: