Amazon/Verizon.
My favorites:
Samsung S-View Flip Cover: http://www.amazon.com/dp/B00ITI22OC/ref=cm_sw_r_udp_awd_nl.Eub14VXFXV
SpigenĀ® Magnetic Clip for flip cover: http://www.amazon.com/dp/B00GXO6UHE/ref=cm_sw_r_udp_awd_.l.Eub170776Z
Lifeproof Fre: http://www.amazon.com/dp/B00K2TD6KU/ref=cm_sw_r_udp_awd_Am.Eub0TB8MK2
Mophie Juice Pack: http://www.amazon.com/dp/B00JOLCE32/ref=cm_sw_r_udp_awd_Yo.Eub03Z0H8Q