Freeware - recommend PIXIA (check Google for it), there are many topics here in the repaint forum that make mention of it. This program is easy to use once you get the hang of the basics, and can produce some impressive results, such as good panel lines and weathering. It also allows layers to be used, making it versatile (and which is also only offered on expensive programs such as Photoshop). Good luck with the repaints.