It would be hard to fathom an answer without seeing sold prices for similar specimens. I would imagine that it could fetch a pretty penny if placed on eBay with great pics and a great Listing Description because even horse turds sell for big money on eBay if it resembles someone or something other than a horse turd.
To me, it appears to be a Iron/Quartz rock that somehow developed in such a way that it appears to have the fossil of a humanoid/bird type entity. Some folks would see a bird while others would see an Angel and the latter is what I see. While it developed naturally, some folks would definitely want the specimen.