Hollow core wood doors work fine for most people, and are an economical way to get doors into a space and have money left over for other items. They come in a variety of styles and panel numbers for looks from contemporary to traditional.

Don't skimp on doors. We bought hollow core Masonite doors for our house to save money. A number of them have holes in them.

6 panel doors or other solid doors often come in MDF painted white, solid wood of various varieties, and wood with solid wood and wood veneer parts mixed - often solid wood panels with wood veneer over MDF for the mullions and rails.

Hollow core doors are the least expensive. You can get white ones formed to mimic 6 panel or other solid wood doors. They are light weight. Solid MDF are more expensive but most expensive is usually solid wood - depending on the type of wood. A solid pine door is not as expensive as a solid oak door. If you plan on painting the door, do not use solid wood, use MDF. If you are replacing hollow core with solid wood be sure your door jam can hold the heavier weight door.