I am not sure if there is a TM issue with UnsolvedMysteries since there was a popular TV show with that exact title. It ran from 1997 to 2002 (or around that) but I think was rebroadcast more recently possibly.
Assuming no TM issue, UnsolvedMurder in org only went for $160 (although back in 2005)
AllMystery, GoodMystery and ShortMystery have all sold in .com, but at surprisingly low values from $153 to $253.
Based on this, I would think low $$$ is the price, especially since net, even though instinctively I would have thought more, like high $$$. I don't feel very sure on this one. Perhaps others can be more helpful. Good luck with them.