The following are materials mentioned in both the books and films as valuable ingredients
and items which come from dragons:
Hide
Used in the wizarding world where muggles will use leather. Especially useful in making protective clothing.
Blood
There are twelve uses for dragon blood, as discoved by Albus Dumbledore. The twelfth is oven cleaner.
Liver
These cost 17 sickles an ounce in Diagon Alley
Heart
The heartstrings are used as magical core substances for wands, much like a phoenix tail feather
Horn
Useful when powdered. Romanian Longhorn horns are Class B Tradeable material
Eggs
Classified as Class A Non-Tradable material due to the outlawing of dragon breeding at the Warlocks' Convention of 1709.
Chinese Fireball shells are highly prized potion ingredients