Amazon's peripheral sale. Controllers, adapters, wires, and even Microsoft Points cards are included, with discounts ranging from 10–25 percent off regular prices. The sale doesn't appear to have a clear end date, so you could have any number of days to take advantage.
In a separate promotion, Amazon is offering a $20 credit toward a future video game purchase (made by March 31) when spending at least $80 on select software. This promotion ends January 2, and the credit will be applied directly to your account after the items ship. Only one credit per household. Void where prohibited. Don't stare directly into the sun. Always tip your waitress.