The way I redid mine was scuffed it with a real fine scoth brite (the gray stuff). I paint preped them, then hit them with a self etching primer & had my body/paint guy paint them with marhide's gm satin black paint. Cost me $65 to redo all the trim.
Powdercoating may be more durable but this way looks original and cheaper. Just my $.02. Its holding up great 2 years so far.