Here is an article that may help you find cheap interior design: http://online.wsj.com/article/SB10001424052748703561604575282512405775480.html Here is another site that may help you: http://www.affordableinteriordesignnyc.com/
An online site that specializes in interior design software is www.homedesignersoftware.com/interior/. After you figure out how you want to design, then you can go to Home Depot to buy your supplies.
There are many sources for you to buy interior design concepts. You can check out blogs, which usually have great information from others who are in your shoes. Here is another source: interiordesignconcept.com/
Interior design software can be purchased at home on your computer and at any home improvement store or at Target. Interior design can also be completed at a college or university near you.
You can purchase cheap home interior and gifts on eBay's website. This online store allows customers to buy and bid on items, such as home interior and gifts.
You can buy wallpaper at interior design shops, online outlets like www.DesignerWallcoverings.com or direct from wallpaper companies like Cavern Home www.cavernhome.com. If you have an interior decorator, they can take care of it for you.
You can buy a book about fabric design on amazon.com which is cheap and including more informations. http://www.amazon.com/Fabric-Design-Book-Understanding-Creating/dp/1579901204
Interior design
You go to a college that offers a degree in interior design.
I bet Interior Design Institute is a scam.
Some classic books about interior design are The Better Homes and Garden books. These interior design books have been around for a long time. Another good Interior Design Book is Home by Design.
Classes on Fine Art, 3D Designs and Interior Architecture are important for interior designing.
The Savannah College of Art and Design (SCAD) has a highly rated interior design program. Visit: www.scad.edu/interior-design The University of South Carolina offers a major in interior design: www.sc.edu/career/la/art.html