The cheapest inground pool to install is a vinyl-lined pool. Installation costs for a vinyl-lined pool can range from $2,000-$8,000, depending on the size of the pool and the complexity of the installation. Steel wall pools are a bit more expensive to install, with installation costs ranging from $5,000-$10,000. Fiberglass pools are the most expensive to install, with installation costs typically ranging from $10,000-$25,000.

There are a few different factors that will determine the cost of installing an inground pool, such as the size of the pool, the materials used, and the level of customization. However, in general, fiberglass pools are the cheapest option, followed by vinyl pools and then concrete pools. If you're looking for a budget-friendly option, I would recommend vinyl or fiberglass pools. Vinyl is generally cheaper than fiberglass, but it may not be as durable over time. Fiberglass is more expensive than vinyl but is more durable and requires less maintenance.