It's hard to tell what this looked like before it broke. Do you have any part numbers on the pieces or on another hinge that is still intact?
We have had pretty good luck finding replacement parts at Al's RV, but they are located only a few miles from our home:
You may have better luck at an RV parts store in your area, where you can take the part in for them to see.
Also, we have also been able to find some parts at West Marine. In most cases, marine parts are better quality than those made for RVs; because they are frequently made of stainless steel instead of plastic or pot metal.