Games, and many other things people buy, are almost always cheaper when they aren't new anymore. A "game of the year" edition released 1+ years after the base game usually sells for the full price of the original game but includes the dlc. If you don't want to pay full price for something, wait until it's old and goes on sale. You (should have) known what you were getting into. If you buy a new next year model car and try to get a free upgrade the following year just cause you got it when it was new, you'll likely be disappointed due to foolish and unrealistic expectations. Same for this expansion.