Where to get key fob battery?
 

Dealer?

Amazon.

Is it one of those batteries which resembles a coin in size and shape? Then go to your local drugstore.

I once ordered key fob batteries from Amazon. The manufacturer packing was about the size of a Postit. Amazon shipped them to me in a box big enough to hold a pair of shoes. When I opened the box, it was empty. My theory was that the battery slid out of one of the areas where the box flaps overlap one another...

i got one free at the service desk of the local dealer.;)

dollar general has them

I would also go with Amazon. Because they are cheap.

A battery at Walmart will set you back about $5 for one. You can get 10 on Amazon for the same price.

It depends on how much time you have. Amazon is going to take a few days, Walmart is right now. But if you put the batteries away and don't forget them you will never need to buy another one because you will have nine spares.