Whoa, what's this about a dragon tooth? I've never seen anything like that before! Tell us how you did it.
In answer to your question: have you been to see Anakin, who leads you to watto? If not, do that first. Then you'll be able to go up to certain people and trade.
Have you tried both options? If you say "I am looking for a T-14 hyperdrive Generator", someone may offer you parts instead.