They are actually designed for airbrushing on Fabrics. They dry quickly and don't rub off easy. Because they are made for textiles their flexibility is superior to other paints. Yet they still wash off easily in soap and water. They also work well when applied by regular bristle brush.
Larger bottles are available, but usually only black and white in most retail outlets.
Createx has an iridescent line of colors that come out quite nice, with a shiny look, as opposed to a matte flat finish. The Jurex colors seem to work better than the Createx when using a bristle brush. They are available at any good art store that stocks airbrush supplies. I use a Pasche airbrush for fine work and a larger production airbrush for large areas. It works well enough, but I found a smaller one at Sears called a touch up gun, which uses a pint size canister.