Homeowners spend about $828 to $12,426 in interior designing services. An interior designer in Vermillion 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.