LG offers an LG G3 Battery and Battery Charging Cradle for $0 with the purchase of any LG G3 smartphone via this rebate. (You can submit by mail or online; the items will be shipped to you upon submission.) That's $85 under the cost of these items sold separately elsewhere. Note that some exclusions apply, including used or refurbished models. The phone must be purchased by September 22, and the rebate expires October 6.

Note that delivery may take up to six weeks.