amazon.com has the Samsung SWA-9200S Wireless Rear Speaker Kit for $90.39 with free shipping.

• Wirelessly connect 2.0 Ch 2 front-firing rear speakers to compatible Samsung soundbars
• These speakers are ONLY compatible with Q600B, Q60B, S60B, S61B & S50B Soundbars from Samsung. They will not work with Non-Atmos soundbar systems from Samsung.