Best Buy dropped the price of Titanfall by $15 as part of a one-day sale for Tuesday, April 8 that included discounts on other games like the 2K Essentials Collection. Amazon stepped up later in the day by price-matching some of these discounts.
The physical versions of Titanfall for the Xbox One and PC are both available from Amazon for $44.99. Unfortunately, the downloadable PC version is still at the regular $59.99 price at the time this article was written.
Killzone: Shadow Fall and Knack for the PS4 are both out of stock from Amazon and are currently being sold by third-party seller at discounted prices plus shipping. That's the similar case for The Last of Us for the PS3 at $38.99 but shipping is at least free and being fulfilled by Amazon. However, Gran Turismo 6 is available for $43.01 from the retailer.
Free shipping is offered from Amazon for orders over $25 or if you have Amazon Prime. Sales tax may be applicable though depending on your state.