I tell people my wife collects funeral pictures of babies, and they say that's really weird, but those pictures go high. So do old coffins. Because you'll know you're getting something better than being in a dank, dark place like sitting in the dirt. If they're in heaven, they've got other kinds of stuff to do. If they're not there, then they've got worse things to think about.
Bones are neat because they're more or less permanent.
The person is dead and gone, but the bones will last thousands of years if taken care of. And they're interesting to look at too. Another collector is David Grim of Winchester, Virginia. As a boy he gathered various small animal bones and skulls, then progressed to larger animals, human skulls, and entire skeletons. He regularly frequents antiques shows in search of human bone medical teaching aids, especially complete skeletons.