For $700 you can buy a MicroFone 2 from Collett Electronics AND a new helmet.
If you want a true wireless solution, do a search for MicroFone 2 on this board as I've been keeping my review updated. I've got rider to passenger, rider to rider, rider to cell, passenger to cell (their own), tunes - in true stereo, tunes to the passenger (their own) and bluetooth to my 2820. All wireless and it works perfectly. 3 year warranty that the company stands behind, its waterproof, sounds great, and Les (the owner) is a member here on this board.
This system just flat out works.