I have used the Sony ECM-AW3 Bluetooth ($170) setup. It is fine as a lavalier mic, but generally too much hiss for ambient sounds. I have also heard good things about the "Rode RodeLink FM Wireless Filmmaker System" for $400. But I prefer a $70 Tascam DR-05 standalone sound recorder, and merge the audio in post. Its got a really clean audio floor, great for when you have to boost the audio level.