Yes, they can be purchased from just a few sources, but for early 64-65' B-bodies only. There are no A-body or E-body hinges in existence that I know of.
These are pure aluminum with brass sleeved steel hinge posts. Add in a set of Titanium fasteners and you can shave off a pound or more of weight.
Kramer Automotive Industries has them at $700 beans. I bought my set at a fraction of that from a cat that had lost interest.