It depends on the wall's size and height. Generally, the taller and thicker the wall, the more expensive it will be. Concrete retaining walls are a popular choice because they're strong and durable, and can last for many years with minimal maintenance.

It depends on what you mean by expensive. A poured concrete wall will be cheaper than a block wall, but more expensive than a timber or vinyl-coated steel wall.It's also important to consider the cost of labor. Poured concrete walls are much easier to install than block walls, so the labor costs will be lower. Vinyl-coated steel walls are very easy to install, but lumber is not, so the labor costs will be higher.So it really depends on your specific needs and preferences. If you want a cheap, easy-to-install wall, go with a poured concrete wall. If you want a nicer looking wall that will last for many years, go with a vinyl-coated.