Concrete Retaining Wall Prices. Concrete retaining wall prices start around $30 per square foot including materials and installation and can go as high as $45 to $50 per square foot depending on how much prep work is involved in building the forms.Walls higher than four feet typically require a different type of form which will raise the cost.oncrete Retaining Wall Prices. Concrete retaining wall prices start around $30 per square foot including materials and installation and can go as high as $45 to $50 per square foot depending on how much prep work is involved in building the forms.