I would check ebay. I was in the same boat, with my tri z, and the needle costing $50 plus! I was on ebay one day, and found a old nos carb rebuild kit that had all the new jets, gaskets, needle and all, for $15. Try different searches, or maybe someone on here would know of a seller that sells these? Good luck!
THE 80's RAGE! Currently owns:
81, 85 Yamaha Tri Moto 125
83 Yamaha Tri Moto 200 x2
82,83 Yamaha Tri Moto 175 project
85 Yamaha Tri Z 250
84 Kawasaki Tecate 250
84 Honda ATC 70
85 Honda ATC 350X
84 Honda ATC 250R
(2) 84 Honda ATC 200x
82, 83 Honda ATC 185s
81 ATC 200
Lots of other parts and bikes