If you look on eBay, under vintage computing, you can get an idea of what the older collectable chips sell for. There is an entire sub culture of people who not only collect the old chips, but also put them back to use in older electronics. A good friend of mine is always looking for the memory boards, for example, that go into old standup video games. Whenever I find older chips in material I get, I check the prices and sell them to collectors if at all possible. These people are actively preserving our computing past and retaining the history, plus you can make a little more than if you processed them many times.
Scott