Where's the coin case in Fire Red?

Once you've got it, have a look round the Game Corner floor. There are coins lying around that only show up with the Itemfinder, and a couple of people in there give you a few if you talk to them. Saves buying your first batch.

It's in Celadon too. Go into the restaurant in the city, the man sitting at one of the tables gives it to you when you talk to him.