Platinum is now so expensive that, over the last decade or so, period fine-art photographic printers have resorted to using palladium. Though a vastly more expensive and tricky substitute for silver, it allows soft and subtle tonal gradiations in a print.
Unfortunately, you have to have a negative that is the same size as the print you want, as you typically use a direct "contact print" technique, with the sun or a very intense ultraviolet light source to expose the emulsion.
It's a challenging technique that has few adherents, though they are very dedicated.
As an aside, one of the easiest and least expensive alternative photographic printing technologies is the cyanotype process, commonly called "blueprinting" (no, it's not just for drawings). When done well, it is strikingly-rich looking.
Photography is a very expensive hobby, but some might say it's cheaper than speculating in metals.