The cheapest pool finish is typically a standard white plaster finish, which is a mixture of white cement, white marble aggregate, and water. It is a popular and affordable option for pool owners due to its simplicity and low cost.

A white plaster finish may not be as durable or long-lasting as other pool finishes and may require more frequent maintenance and resurfacing over time. Additionally, white plaster can be prone to staining and discoloration over time due to exposure to chemicals and sunlight.

There are other pool finishes available that are more durable and long-lasting, but they are typically more expensive than white plaster. Examples of these finishes include pebble, tile, and aggregate finishes. These finishes offer a variety of colors and textures to choose from, and they can provide a more customized and upscale look for your pool.

Pool finishes will depend on your budget, preferences, and maintenance needs.