Here's a lower cost idea, that has been used successfully, in an email that was forwarded to me:
"I notice that you do speak audio here from time to time and thought I'd share a new toy I learned about from my sister.
She is using an iRiver <
http://www.iriveramerica.com/products/H140.aspx> in
place of a wireless transmitter. Her Tram micworks fine with it and she does not have to worry about radio integrity when shooting.
She also runs an on camera mic for ambient and to get her interview questions and such. She then syncs up the iRiver audio in post with FCP.
So far it has worked like a champ. It is alsorunning and getting the subject when the camera is not rolling. Sometimes she will use one of those lines over a bit of B-roll.
Recently I turned a friend onto this trick for a surfing film he was doing. They sealed an iRiver and put it on a surfer with some cheap lav mics. They killed a few mics, but they got good track."
<L>