I love the idea! Instead of buying a whole closet full of high heeled shoes, you could just purchase individual components such as heels, straps, buckles, and so on. Maybe you can't afford the newest shoes from Louis Vuitton, but maybe it was only the designer heel that appealed to you anyway. So instead of paying $1400 for a pair of shoes, you could now buy a pair of screw on heels for a significantly lower price and create your own look.
I would like to purpose the multipurpose "Retractable Heel." Go from flats to pumps to stilletos within seconds at the touch of a button, flick of a switch or whatever clever method the engineers develop. You can keep a set in your purse alongside your swiss army knife. http://apocalypse-diy.squarespace.com