Homeowners spend about $780 to $11,712 in interior designing services. An interior designer in Lone Tree may charge $50 to $200 per hour. Some will charge their client by the cost up method or by marking up the cost value of the decorations, furniture, accessories, and artwork that will be purchased. A usual markup starts from 15% up to 25% of the goods purchased. Another way that an interior designer charges their client is by a fixed or flat rate fee. This is mostly applicable to large scale projects and the charged amount usually covers all the expenses that will be incurred during the project.