You can buy kids sixed northface jackets from the northface company. If you are looking for a cheaper buy, you could look for new or used ones at a discounted price on ebay.
They are available in wide variety of colors with wide variety of styles and thickness. Some are pink, blue, green, purple and other colors that is in a crayon.
North Face jackets are sold at a large number of outlets. Any company that sells above average camping equipment will be selling North Face jackets, or at least can tell you where to find them.