I've been looking for something like this for my iPhone 7, this is the cheapest I've found. Usually around £20.
Convert any earbuds or headphones into wireless Bluetooth headphones. Great for future devices without a headphone jack. 50ft (15m) wireless range. Built-in microphone for hands-free calls. Compatible with Siri, Google Now and other voice recognition apps.Use code BOXV5 for this priceInfo on Griffin Site