There is no definitive answer when it comes to the cheapest style of pool. It all depends on a variety of factors, including the materials used, the size and shape of the pool, and any special features or amenities that you might want to include. In general, however, above ground pools are typically more affordable than in-ground pools. Other cost-saving measures you can take include choosing a basic design without too many bells and whistles, and opting for a smaller size rather than a large one.