Lemme see here - they ripped you off by offering you a price, having you voluntarily agree to the offer in the form of a binding contract, and now they are delivering what you agreed to at the agreed upon price. How dare they!!

Every component of travel - air, hotel, car rental - has prices that fluctuate constantly. You are responsible for researching your options and only agreeing to a deal when it is satisfactory to you. Prices go up and they go down. If you are satisfied with a deal, making it cheaper later shouldn't change your satisfaction - you exchanged the certaintly of locking in a reservation in exchange for the risk of higher or lower prices in the future.

What would your response be if they called you and said the price had gone up - please forward $200 to make up the difference?