I find that analogy very bad. It would be more like you buy a Sodastream (that can make carborated water). When you want to refill it you have to go back to Walmart. You are not allowed to go to any other store, including Sodastream. Even if you order a refill gas bottle from Sodastream directly the payment will have to go through Walmart since you bought the machine there a long time ago. And they will add 30% to the price.