There are a number of places selling "special" paint for fabric at 4x the price of other comparable paint. What makes the "special" fabric paint so special?

I'm more than skeptical about this and feel that on a clean surface, a coat of primer and spray lacquer color should work as well as any other type of paint. Anyone have experience using just simple cans of generic, cheap Home Depot spray paint?

This is the chair - I have 4 to do. The cushion covers don't come off (no zippers) and my ability to sew is non-existant, besides by the time you do the work and buy the material you're paying top dollar anyway. Worse yet - the cushion sizes are proprietary and discontinued, so even buying replacements is out of the question.