Homeowners spend about $879 to $13,205 in interior designing services. An interior designer in Holden 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.