What fossils are good to buy

The old saying, Beauty lies in the eyes of the beholder gees to mind here. A couple years ago I won an auction for a piece of ulna, larger forearm bone, of possibly a T. rex. It didn't mater to me if it was a T. rex or not, the fact that it was theropod was cool enough for me. It showed the structural framework so like that in birds today. I was tickled pink as it were.This is what a fossil should do for you. Make you excited and wanting to investigate each and every nook and cranny it will show you. If a piece of tooth is what you like, go for it. I like the broken bone sections because I also make thin sections of them, a slice of the fossil so thin light shines through which has been glued to a microscope slide for study.