This isn't talking about the store. No you probably shouldn't be allowed to say "Go here to buy this app for cheaper" in your App Store description. But inside your app, you most certainly should.
Physical goods are not the same as digital goods, but even if you do want to go with your analogy, brands will often times include coupons and refill offers and other promotional material with items they sell and push the consumer to buy directly from them and retail stores still carry their products.
Physical goods are not the same as digital goods, but even if you do want to go with your analogy, brands will often times include coupons and refill offers and other promotional material with items they sell and push the consumer to buy directly from them and retail stores still carry their products.