Just look up Electroplating in the yellow pages. I'm sure there is someone close by that does it. I had my Challenger fasteners replated at Key City Plating in Dubuque. They had a base charge of $40 for barrel plating. If I would have been organized, it would have only cost me $40 to get every zinc plated fastener for the entire car done. I ended up having to do two batches. Hopefully the Dart is a different story.
I actually brought the fasteners with me today to drop off. I found a place in Cedar Rapids so that's a lot closer then before.