this is an excerpt from http://www.mobileinfo.com/Bluetooth/FAQ.htm
Q: What is the range of Bluetooth transmitter/receivers? A: Bluetooth is designed for very low power use, and the transmission range will only be 10m, about 30ft. High-powered Bluetooth devices will enable ranges up to 100m (300ft). Considering the design philosophy behind Bluetooth, even the 10m range is adequate for the purposes Bluetooth is intended for. Later versions of the Bluetooth spec may allow longer ranges.
and possible headsets are from(site only for examples of bluetooth headsets,please do see other sites) http://www.mobilecityonline.com/wireless/store/productaccessory.asp?productid=22709
as mentioned the maximum range is 10 m,do see if that helps u..also bluetooth on can drain the battery faster..
hope it helps!regards!