Ducklakeview said:
One of mine is playing up, so just ordered a couple of these http://www.ebay.co.uk/itm/433Hz-Remote-w-CHIP-TRANSPONDER-For-BMW-E46-E39-3-5-7-Z3-M3-M5-Keyless-Key-Fob-/152529163109?hash=item2383725365:g:0yEAAOSwt0FZBAqL for £8 each! Gonna have a go at programming them to my car myself..
Mike
Yeah, I saw those but they don't seem to be compatible with pre 2005's

.
I had to reprogramme both my keys after the recharge of the dead one. I used method 2 on here:
http://www.programyourkeys.com/BMW_Z4_Key_Remote_Control_Fob_Programming.html
Worked no problem