I belive that you can find one in cerulean city where the old man is (this is just an answer i got crystal on PlayR.net) but other than that tehre is a man that asks to see some pokemon and one of the rewards you get is a fire stone (there is also a bug catcher at one of the routs that will ask for your pokegear number and he will call you with something rare (usually) i hope your not in a hurry because those are the only ways unless you got a friend with a gameboy who has a fire stone or a aracanine (i know ya want it cuz everyone does)