LonglyThis does come with the expansion, though. $14.99 here with $5.35 shipping at the lowest price is $20.34.
CSI has the core game on sale at $7.99 with the expansion normally at $5.49 with $7.41 shipping (for me)... This makes it $20.89. My level-based discounts bring it down to $20.69.
So Massdrop, if this hits the lowest price. will save you a couple cents. After Nov 1st this will be the lowest price definitely.