I'm not real sure how much an informational website would be about the Jonestown massacre would generate. I guess with enough traffic it would bring in a tiny bit from advertising but in reality, how much traffic per day would a site like this even get?
This would greatly determine the value of the domain.
Even if the website had a #1 Google listing for Jonestown, you might bring in about 1,000 unique visitors per day. With a really well developed informational site this might bring you in a small amount in ad revenue but not enough to warrant a heavy investment in this domain and that hurts your overall value.
I would say honestly you might get a few hundred for it undeveloped but your best bet it to develop the site and try and generate ad revenue.