Yes, JC Auto Restoration, Inc. in Lynwood, WA is the sole distributor of reproduction door sill plates for 57 - 59 Dodges. The plates are made in Sweden to the highest quality standards. They are $385 a pair. The website is:
That company is a great resource for a lot of parts and refurbishing of the older Chrysler cars, and I have used them often. Jeff Carter runs it and he is top notch.
Your 57 Dodge, assuming it is the one in your avatar is a nice looking car. There is one almost seemingly identical to it for sale on ebay right now: