Pricing for discounts and “teaser” rates for new customers are two very common. Marketing strategies. There is a large percentage of consumers who react positively to sales and discounts, irrespective of net price. They will choose the item listed at $50 with a 50% discount over the exact same item at $23 in another store.
Similarly, customers have been shown to have a reluctance to price shopping and changing providers on recurring purchases. Once the customer is secured by that teaser rate, they often become customers for life who are very price insensitive. Good Sam is an avid user of both of those strategies.