Most of those look to me to be books that would sell for a couple of bucks. The Tarzan book and the Davey Crockett book might surprise me, but the value in the Tarzan book would probably be heavily tied into the dust jacket, which seems to be missing. The last book would be my best bet for some real value. Checking ended auctions at eBay or doing a search through Alibris may give you a idea of value. Either way, if you are getting them for a buck a book, you ain't getting hurt, and you might hit a home run sooner or later.
Couple of things, old in books does not necessarily mean anything in value. A Stephen King first edition from 10-20 years ago is often a fairly desirable item and often has some real value. As a general rule, I would say that non-fiction books tend to have a better shot at value than fiction. The more obscure the subject matter the better, but finding the buyer willing to pay is another matter.