Sure you can do this.
The Jabra BT200 is designed for non-BT phone but becasue the earpiece is BT you can use it stand-alone with your 7100. It's what I do.
http://store.bizshopr.com/jab9103r.html
We have a FREE Shipping offer on this unit.
http://www.blackberryforums.com/viewtopic.php?t=1374