I don't have any problems with it yet but I would like to find a place first before I need one since the car is 4 years old. My friends died at 4.5 years and he got stuck and had to get it from BMW and I think he spent almost $260.00 on it. It would be nice to have one lined up in case I do need one in the next year or so. I might even just order one without the acid and just stick it on my shelf, always good to be prepared.
I keep all sorts of stuff in the wings, tire plug kits, battery jumpers, etc. Have used all at one time or another and it has saved me a bundle. Keep spares in my car as well.