Look at it this way .... if you can't find a replacement, why not try to repaint anyway. If the stove top looks bad, what will it hurt anyway? (my philosophy is, if it's broke, I can't break it any more, so why not try to fix it. If I can fix it, I've done well. If I break it more, well ... it was broken to start with .. what did I loose?)
They make high temperature paint for repainting barb-b-que grills, Lowe's, Home Depot, ect which do work pretty well. Metal sand any rust or existing paint flaking areas and smooth it down. When you're done, it will look like new.