[Anders]

Have you looked at DF8: Treasure Tables? Common furs are worth $200 per 75 lbs., while exotic furs are worth $500, 75 lbs., etc. (p. 12). The fur of a bear weighs 50 lbs. It has DR 2, which would probably be relevant for the weight - say that the fur weighs 1/5 to 1/20 of body weight (this is off the top of my head, I have no experience with hunting). I couldn't find any information on horns and antlers, etc. though. They can be used as decoration, I suppose. Still, DF8 would be where I would look.

If there is no listed weight I would say... 1dx$100? Lots of cutting damage would reduce that, obviously but that might be going into too much detail for a DF game. It depends on how much loot you want them to get.