One of Ponyville's many small businesses, Bait and Switch Specialties of Ponyville is notorious for having great prices, but not carrying whatever it is you may happen to be looking for. They are particularly well known for their advertisements, a typical example of which might go:
"Bait and Switch Specialties of Ponvyille is your number one source for flies, lures, earthworms, and light switches!
...Actually, we don't have any flies, or lures. We just ran out of earthworms, and we're expecting a shipment of light switches next week.
But we do have lots of things that are almost as good and a LOT cheaper!
Bait and Switch Specialties: come for the savings, leave with a surprise!"
"BS of Ponyville" (as Applejack referred to them) was sued by a pony named Sweetilou Blue, who came into the store to buy bait, but ended up leaving with 200 lbs of nails at a great price. Applejack, who was temporarily acting as the civil court judge at the time, ruled in favor of Bait and Switch, but referred to their advertising practices as "shaky."