Best Buy is offering a $100 gift card with the purchase of any Xbox One in a special Presidents Day promotion. The gift card is valid for purchases at Best Buy only.
The promotion is shown in the body text of the product itself. Scroll down the page of the Xbox bundle you're interested in and make sure that you see the graphic below indicating a "free bonus item." It includes the vanilla as well as the special edition models, including the Halo 5: Guardians edition ($499.99) and the Elite ($499.99).