They should be just in the store, every town has another stone
Chat with our AI personalities
you can find one at the power plant
Talk to the worker guy on the top floor of the Route 9 Shopping Mall. He will give you a Thunderstone.
Catch a Pikachu, which you can find on Route 2, and use a Thunderstone on it.
In Pokemon Black and White you can find a Thunderstone in these locations: Route 9 and Chargestone Cave. Sometimes, a dust cloud will appear and you could get evolution stones or Gems. These are the locations where you can possibly find a Thunderstone in: Wellspring Cave, Chargestone Cave, Mistralton Cave, Twist Mountain, Challenger's Cave, Victory Road, and Giant Chasm.
Yes you can. From a walkthrough, a person claimed that he received a Thunderstone from someone from Olivia City. It's a "she" that you have to battle and get her contact. Pretty easy though =]