10,000 coins at Veilstone Game GCorner
Go to Fuego Ironworks (Go west along the river at valley Windworks) and enter the factory.
There are 3 trainers, mainly machops, Ponytas and Rapidashs. Beat them, get the items if you want, and talk to the man at the end.
He gives you a Fire Stone (Evolve Eevee to Flareon if you want) but if you grab the Pokeball behind the furnace, that holds Flamethrower!
Hope This helps