What fillers are you talking about? The front ones or the rear ones? They are different.
The rear ones get painted with textured argent paint along with the tail panel and tail light housings. The front fillers are NOT painted at all. They are just the natural gray color of the rubber.
You can spend a lot of money to get the correct argent from Frank Badalson.......you can buy both the light and dark argents from Totally Auto and mix them to get close to the right color......or you can look for Krylon Fusion textured paint. The Krylon paint comes in about 5 different colors. There is one color that is a decent match to the original argent paint.
As far as the front fillers are concerned...if they aren't that bad, you can clean them up nicely with some very fine wet/dry sandpaper. My front fillers cleaned up nicely without needing to be painted.
rear fillers painted with Totally Auto argent.(both light and dark mixed to get close to the right color)
front fillers wet sanded...no paint