If you are not certain of your ability to properly care for it, I would make an appointment with the conservators of a major museum and A: verify that it is in fact a Hillotype, and if it is genuine, donate it for a fat tax write-off, or B: contact Sothebys and/or Christies auction houses and see about putting it in a sale. They're very rare beasts so I think valuation would be hard to determine but it would definitely be valuable.