I was just wondering where I could buy the evolution stones necessary to evolve certain Pokémon.
You can get one each of the Evolution Stones, by going to the Sea Cottage on Route 25 in Kanto. Show Bill's grandfather a Vulpix or a Growlithe for the Fire Stone, a Pichu for the Thunderstone, and a Staryu for a Water Stone.
You cannot buy them.
You can only get them from people or places.